Hello I have asus rog zephyrus m gu502gv. I wanted to clean it and change the thermo paste (it was stored for a long time and there was a lot of dust, when the game was turned on, the temperature rose to 95 degrees), opened the laptop, turned it off as it should be on both sides, changed the thermo paste and assembled it. it turned on the first time, the coolers were spinning, but then it turned off. now does not turn on at all. everything seems to be done graciously and everything is connected but still it happens and does not turn on, no reaction,. did you have such a case? can you advise anything?
Are you sure when you disassembled your laptop you didn't have any static energy in your hands (or just to stay safe used an anti-static wrist strap?) Is the room too dry? A dry room is a haven for static energy. From your description, it does seem like a static discharge which means the motherboard is fried.
After applying the thermal paste, double-check the heatsink and screws to make sure that it's clamped down securely.
Verify that there is nothing on the motherboard that could possibly cause a short-circuit (foreign objects, possibly excess thermal paste that might have oozed out around the heatsink, you never know).
You've probably already carried out the steps above but it doesn't hurt to double-check again.
If everything looks good but the problem remains, perhaps these instructions could resolve your issue: