When things go wrong ...

That's what we're talking about here and what we can do about it. First let me say that misrepresenting a problem to try to benefit from a warranty you may not be entitled to is fraud. Deliberately damaging the phone in a way that would cover up the original fault is just as illegal. I would never recommend a felony as a solution to a problem.

What we are talking about here are options within the original terms of your warranty. Many manufacturers include clauses about modifying the stock firmware voiding the warranty, but it is more to prevent users from flashing their phone and then seeking support for Cyanogen or SuperDuperOverclock rom 2.4356433.1a. It is up to them to honor or disallow a warranty claim. If it's a carrier subsidized handset the incentive for them to keep you as a customer becomes greater. The real money is made from the contracts, not the hardware.

So you contact the warranty department, either directly with the manufacturer or the carrier and you tell them "the phone isn't working correctly." Tell them what you have tried including battery pulls with and without the USB charger, holding power button, factory reset key, etc. and the phone continues to misbehave. The issue you an RMA and you send it back.

Depending on the company they may try and fix the problem with your phone but many times they will simply send you a refurb as a replacement and send your original phone to the returns department to be wiped, tested and put in the queue as a replacement refurb device. The issue arises if they determine that you have modded you phone's stock firmware or flashed alternate firmware. Most likely in that case they will contact you and notify you that the warranty doesn't cover this and let you know what the fee for the fix. Or, they might not, but that's up to them because you were the one who took the risk in the first place by flashing the phone and possibly being the cause of the problem in the first place.

The other dilemma is what happens if they specifically ask you if the firmware had been modified prior to accepting the return. That's an issue of conscience. Personally I wouldn't want to be looking in the mirror every morning and seeing a cheat and a fraud and compromise my karma for a hundred bucks. Plus, if you get caught, they are much less likely to be sympathetic and quite possibly presecutorial.

The long and the short of it is if you behave in an honest and upstanding manner, you may find that manufacturers value you more as a customer and are willing to cut you some slack. Worst case is you have to pay a little more out of pocket for your mistake, but that's all part of being upstanding and you'll be better off for it.