Remove the gpu and plug the monitor into the mobo.
Do you get a display?
Try to figure out where this liguid on the gpu came from.
Using a cpu water cooler?
I was playing Destiny 2 when suddenly my computer shut off. There were no warning signs of impending doom. It restarted automatically but I had no signal on my monitor. My GPU has no fan spin, no light, and no image. I swapped HDMI ports, I swapped GPU power cable ports on my PSU. Nothing. Upon further inspection I found a rubber strip on the inside of the GPU shroud, maybe to provide support somehow, I'm not sure why it's there. A large area around this strip on the circuit board was wet. So...was this sudden death caused by liquid damage from moisture building up over time? Or is my PSU a ticking time bomb that's going to take the next GPU or the entire machine with it in the near future?
msi z97 pc mate
sapphire nitro+ rx 480 8g (r.i.p.)
evga supernova 650g
intel i7-4790k devil's canyon
corsair vengeance 1600 mhz 32gb ram
samsung 500 gb ssd (evo something rather)
3 hdd's from various brands 7200 and 5400 rpm drives
everything's about the same age, around 3 years old except for the hard drives, them suckers are old