Either your USB thumb drive is broken, or the specific USB port on your MBP is.
The easiest way to test is for you to plug another USB device to the same USB port, then
- Locate the Apple logo on the top left corner of your display, and click on "About This Mac"
- A window will appear. Click on the "More Info…" button
- If you're running OS X 10.6 Snow Leopard, skip to the next step. If you're running OS X 10.7 Lion, another window will appear on which you'll have to locate and click on the "System Report" button.
- A new window will appear, on the left column, locate "USB" which is listed alphabetically under "Hardware". The details of the USB device you connected to that USB port should be displayed. If it is, then your USB port is working normally, which means your USB thumb drive is the problem.
I run into this as well with our MacBooks after a few years. You have to replace the battery. If you have an Apple Store or Reseller nearby, ask whether there is a replacement program ongoing (there sometimes is) which would allow you to get a new battery cheaper or for free.
It would be odd to have a 2008 model Mac still covered under a one year warranty. Even AppleCare with a three year coverage would normally be expired in this case. You might need to spend $129 for a battery at this point, but you could try one more time at a store if you read up on some details.
Towards the bottom it says:
However, the AppleCare Protection Plan for notebook computers does not
cover batteries that have failed or are exhibiting diminished capacity
except when the failure or diminished capacity is the result of a
manufacturing defect.
Then you'll want to go to the full AppleCare document, http://www.apple.com/legal/applecare/appgeos.html, where if you search for battery and skip past the iPod parts, will be:
- What is not Covered?
4.1 Hardware Service. The Plan does not apply to:
(vi) Consumable parts, such as batteries, except in respect of battery coverage under APP for iPod or unless failure has occurred due to a defect in materials and workmanship;
So, with a battery that is rated at 300 cycles, and is listed as a consumable part (i.e. expected to fail over time), it's pretty common for some people with failed batteries to have to pay for a replacement. Now, the one thing would be if the trackpad still doesn't work after you paid for a battery exchange, I would ask them to consider repairing that.
Keep in mind - the warranty (or care plan) has a start and end date. During the time of the plan, it's Apple's responsibility to pay for repairs and service and parts for covered repairs. After that time, it's the consumer's responsibility to pay.
I would head to the genius bar, with an appointment, and ask them to look it over. Explain (briefly) that you were told at another store you had to pay for a battery and feel bad. You clearly wish it had lasted longer and ask if there is any way they could help you avoid paying for either a repair of the trackpad or a replacement of the battery.
Think of that person as your friend as opposed to someone "working for the man" and is there to say no. You might still get a no answer, but at least you read up and can talk with them over what would be covered and what wouldn't be covered. By trying to get a second hearing of your situation, you might either feel better or they might find a way to help and you'll be out a trip to the store and maybe the cost of a battery.
Best Answer
Safety and reliability
In this context, "safety" refers to a products ability to function as advertised with no adverse affects to it nor the device in which it interfaces.
Why wouldn't it be safe?
The idea behind standardizing on USB is so that you can plug in 3rd party devices to expand and enhance the functionality of your computer. If plugging in devices voided your warranty, they wouldn't put the port there and instead we'd still have (our cherished) MagSafe power connectors.
If it wasn't safe to do something, the manufacturer wouldn't market that function as a feature of the product.
Power Delivery
Technically speaking, anything you plug into your laptop has the potential of damaging it.
Since USB 1.0, power has always been supplied - 5V @ 500mA. It is only since the USB Power Delivery Specification was implemented that more power can be delivered; up to 100W or 20V @ 5A.
This is why you should always stick to known brands and avoid the cheap knockoffs.1 It's a timeless adage - you get what you pay for - but it still holds true today. That said, it still doesn't rule out the possibility of a manufacturer defects. While very rare, they do happen; your expensive Dell or LG could potentially damage your MacBook.
If you are plugging in a display that provides power and conforms to the USB PD specification, especially if it's USB-IF certified it's not "non-standard." That device is designed to connect, interface with, negotiate, and accept power. You plugging in this device, does not void your warranty.
Apple decided to go from a (beloved) proprietary power connector - the MagSafe - to a widely adopted industry standard connector that literally has "universal" in the name: USB-C. Simply using a different charger doesn't void your warranty. If damages arise because it was defective, that's a different story.
Is the Macbook 12 inch's USB-C charger interchangeable with other USB-C chargers or devices?
From a pragmatic point of view using your Dell or LG monitors as the basis of your postulate, how can you possibly have a "genuine Apple" charger coming out of a third party monitor? This would mean that the moment you connect a non-Apple monitor you void the warranty. Until recently, Apple had exited the display business when they ceased production of the Thunderbolt Display in June of 2016.3 The display provided charging via a MagSafe connector; the Thunderbolt port didn't supply power. Therefore, it would be virtually impossible to "officially" charge a later model MacBook with this display.
Warranties
Speaking as someone who worked in product management for a hardware manufacturer (in a past life), there are no agreements between companies that spell out any sort of liability assignment or otherwise with respect to each other's hardware. From a practicality standpoint, this would be absurd - think about how many display vendors there are. That alone would be next to impossible to manage. Now, expand that to all the different USB devices and accessories. There's no way to manage warranty reciprocity agreements to that scale thus making it totally unfeasible.
From the perspective of the manufacturer, the warranty generally covers the products fitness or in other words, it's ability to do what it says it will do. If you read the fine print, there will always be a clause exempting coverage for misuse/abuse.
From Apple's own warranty language, they basically say this:
What Voids Your Warranty
In short, misuse, abuse, and anything that's covered in the warranty language. Ultimately, it comes down to what you can prove. Here's a short excerpt from the hardware warranty; I encourage you to review the whole section at the link provided.
Can Apple Void Your Warranty Solely for Using a Third Party Accessory?
No. The Magnuson-Moss Warranty Act4 (in the US, your country's laws may differ) gives protection to consumers in that installation or use of third party accessories cannot void the warranty unless they it can be proven that the part or accessory in question is the reason for the failure.
The FTC (Federal Trade Commission) specifically addresses this in warning letters sent to several companies5:
(Hover for Opinion)
Legal Disclaimer
I am not a lawyer; more importantly I'm not YOUR lawyer. I don't play one on or for any content provider. While many references have been made to legislation as well as agency opinion in this answer, my opinions are my own and should not be construed as legal advice. Seek out your own lawyer if you have a specific and/or real world question.
1 Cheap USB-C Cables Could Kill Your Phone or Laptop; Gizmodo, Feb. 2016.
2 Apple One Year Limited Warranty- US ; https://www.apple.com/legal/warranty/products/embedded-mac-warranty-us.html
3 Wikipedia: Apple Thunderbolt Display
4 US Code - Title 15, Chapter 50, Sections 2301-2312
5 FTC staff sends warranty warnings; Federal Trade Commission Business Blog; Fair, Leslie; April 10, 2018.
6 FTC: Ignore That Sticker Saying Your Warranty Will Be Voided; Laptop Mag; April 11, 2018