Greetings,
Cleaning thermal paste from the top of the CPU should not cause boot failure. Of course if any cleaning fluid got underneath the CPU this could cause a problem. Static electricity as well, but you really have to shuffle your feet on the carpet and touch the board for something like that to occur.
Are you sure you reconnected the CPU Fan to the correct Fan header?
If you've never cleaned a CPU before, I usually recommend removing it and placing on a piece of foam. This ensures nothing gets on the board and also protects the chip. Q-Tips with alcohol work best. I also wear latex gloves as I never touch components with bare hands. You don't have to do this, but I don't like any fingerprints.
I typically use a credit card and toothpick for helping others with bent pins. Its one of the more reliable methods.
I watched your boot loop video. The system is failing to initialize. Since we aren't there to see the board, its difficult to advise and can only speculate what might have happened. I'd start by removing components leaving one stick of ram. Also remove the vid card and test with onboard video. Recheck your connections. You've already done the pre-requisites, reset the CMOS, etc.
Hi, first of all thanks for the answer. This is not the first time I do this, but it was the first time I did with my current setup. In the past I had no issue with the 2500k and a CM as cooler but this time I was using a different cooler I had no experience with and that gave me troubles to install it back in, there was a little bit of movement. The cpu hovewer shouldn't have moved from the socket though, the retainer was on.
I tried both cpu fan connectors, the usual one and another called 'cpu_opt' or something, no luck with that. Gigabyte reached out to me in the support ticket but there's not much they can do, they told me to rma it with the store but the warranty is long gone now. THey also gave me instruction to test the system but I have already done that (cpu, 1 ram, 1 hdd, clear cmos, battery removal, etc...). I tried mostly everything.
One thing I noticed this morning was that the board was trying to boot itself from both bios, after three failed tries it switched bios but I don't know if that's relevant, I don't think two bios could have been damaged at once.
A toothpick is what I used to try to fix the pins, but it's a little bit messy, too much force and you can easily break a good pin, plus I really had a bad time using my augmentation light because I needed to put the board closer with one hand and then I barely had any space between for the other hand. I guess you used the credit card to stabilize the process or something? Might give it a try.
This is an album I made yesterday for the support ticket of Gigabyte. As you can see from the overview there seems to be something in the top side (from the photo's angle) of the socket. The second picture is a close-up from that part, pins seems to be mostly ok but there's something brown/grey under them, dirt? Also you can see pins 1st and 4th from the bottom row are a little bit twisted, those two were looking backwards and I tried to fix them as best as I could, I don't know how can I put them straight.