Xbox 3 Red Ring Error I Have Fixed It Before but When I Used the Same Guide to Fix It Did Not Work Please Help?

I fixed the 3 red ring of death before with an guide we bought online after that it was fixed and working for about 5 months. We used the same guide on it and did the same steps but after we put it back together and turned it on it came up with the 3 red ring error again why did it not work like the first time? please help

Suggestion:

Unfortunately if it's come back after a fix you may be screwed, I'm sure it wasn't a "proper" fix but more a trick to get it working again, not including the towel trick mind you, maybe the penny thing or resoldering or putting Arctic Silver on it. What may have happened now is the GPU (which is almost ALWAYS the culprit) has completely burnt itself out. There is a way to turn on the xbox and hit a sequence of buttons to find the exact hardware error, I think you have to press the wireless button and the power button, but I'm not 100% on that, the sequence of flashes corresponds to numbers, and then you can look those up to see if it's a specific error or General Hardware, if it's the latter, call Microsoft. They know about this problem, and 9 times out of 10 EVEN if you have opened it, they will fix it for free. I had the same with mine, that I got from a friend, opened it up and did all that, only to realize it was under warranty, called microsoft explained how I sold all my PS2 games for Xbox games by the way, and they told me to ship it to them 2 weeks later got a working xbox, probably just changed the motherboard though.

Unfortunately I think it may be burnt for good. =(