Bass Face SQ1.1 Amp turns on and off.

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I'm new to the forums, I hope this is the right place to post about this issue.

I've had the amplifier for about 6 months now, it's been powering an Alpine SWR-12D2 and it's got quite a lot of power for the price, and it's been working flawlessly until recently. I should mention that I'm using it at home, powered by a 3kW server PSU that provides a constant 12.6V.

I'd have it turned on for the whole day, every day, no problems, no overheating, but one morning, when I decided to turn it on, it turned the ON light for a split second, followed by the protection light for a split second, and then it shut off my whole system, including the PSU. The problem is not the PSU as I am powering another amp with it, Bass Face DB4.1, and I've had that one for about 2 years now with no issues at all.

I did open up the amplifier, checking all the components, and nothing seems blown, as I never get close to it's limit, I've never felt it go remotely warm. No burnt smell, the connections are all looking intact. The funny thing is that when I was taking out the board from the body/heatsink of the amp and putting it back together few days ago, it managed to turn on and stayed on! So I thought I had fixed it, but later I found out that only sometimes it turns on and stays on. It's a really weird problem, I'm pretty sure it's something got to do with the grounding, because if I screw in the ground wire really tight, it couldn't turn on, then I loosened the screw a bit and it turned on, but then later on it wouldn't turn on and would only turn on if I secured the ground wire tightly. I cannot explain what is going on, the amp literally is the one to decide when to work and when not to.
That being said, when it does turn on and remain on, it stays on until I decide to switch it off, I can be playing music extremely loud, nearly burning my 1000W RMS sub, so putting load on it is not an issue. The issue is the turning-on stage. Sometimes it decides to turn on and remain on, most other times it doesn't.

If anyone has encountered a similar issue with their amp and knows how to fix it, or anyone who has more experience on the matter can give me some helpful advice, I'd be extremely greatful, as I've 2 Monacor Carpower Sonic 15" ordered and I'd like to use that amp to power them instead of having to buy another one now... :/

Sorry for the huge amount of text but I just wanted to describe the problem in depth so that a solution can be found quicker.
 
Bump:
I did forget to mention that there is no difference if I have RCAs and speaker wire disconnected, the amp still experiences the same issue. I would only have the power in, remote and ground connected and it's still acting up. I thought that something was touching off the heatsink on the underside of the PCB, so I insulated it with paper, it still experiences the same problem.
The thing I find most weird is that it sometimes does work, when I literally do not touch/change anything.
For example, I can try to turn it on, and it won't stay on. I can try again a second time, it won't stay on. I can try a third time, same thing, BUT then the fourth time it would turn on and remain on. All of this happens while I'm simply toggling on/off the switch I've connected to the remote wire, not messing around with the ground wire screw or anything.
If it was a logical problem, I'd have it sorted out by now... Please can someone help me out with this?
 
Have you tried getting the schematic diagram from the manufacturer?

This amp seems to be fairly complex and I have no experience with it or any similar amp. If no one can help, you may have to measure the voltage on the various power supply and protection ICs and compare the voltages when it's working normally and when it refuses to power up to see which points are different.
 
The company isn't exactly a well known one, and most of their products are really cheap, with my amplifier being the most expensive/highest quality one from the brand. That said, I won't be able to get the schematics I bet, I have sent them an email requesting it but they haven't replied, which also goes to show how great their customer service is.

I will have to open it up again when I get back home to check those components with the DMM. As I said, nothing looks burnt or smells burnt, as I like to take good care of my amps by setting the gains properly with an Oscilloscope and never turning it up even close to the clipping point. The PSU providing power couldn't have done the damage either because it's giving out such clean power, never ever dropping from 12.62V.

None of the components are shorting to the casing as I've insulated every inch of the case on the inside to make sure nothing is touching.

I'm guessing the problem can only be a defective component, however I wouldn't know why as I've had it for a short enough period of time, never having issues with it and never abusing it in the slightest.
And even then, that still doesn't explain why sometimes it turns on and stays on for as long as I keep it on, but then other times it won't turn on. I've looked everywhere on websites and forums and nobody seems to be having that exact same issue, so it's really frustrating.
 
Bump:
I got to work on the amp a bit today. I opened it up and checked once again if anything is touching off the case, and it isn't.

I know it's a silly thing to do, but I wanted to try feeding the amp only the power cable to the +12V connection, WITHOUT feeding the ground wire to the GND connection. The amp worked that way, every single time, but of course the audio is terrible and barely any power is drawn because of not being grounded. How is there any logic in this?

I'm sorry for not trying out the method that Perry Babin suggested, I am not ignoring it, I just wouldn't have as much time to do it right now and I wanted to try out everything else before I had to go ahead and measure the voltages of components.
 
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