Acer aspire 5750g shuts off with a weird internal noise


Mar 16, 2016
My laptop (Acer Aspire 5750g) had about 6 years of extensive use, I experienced first troubles with it a year ago (first, built-in keyboard started to fail to register button presses or registered false ones, so i disconnected it and used an USB one; second, nvidia card began to get driver faults, i fixed it by lowering core and memory clock a bit with MSI Afterburner). A couple of weeks ago it just suddenly shut off as if it lost power while i was watching something on Youtube with Photoshop running in the background, I turned it on just fine afterwards. Then it started to shut off in this manner more and more frequently, often while running a game or multiple graphics editors, always with a sound similar to a sound of rapidly spinning disc hitting a wall and jamming (I checked all rotating things - cooling fan and HDD - those are working properly) or a powerful electric spark. And on attempt to turn it on afterwards I get just a blink of all appropriate LED indicators (power, hdd) and the similar sound, only shorter, like click, nothing more. A few hours later it turned on appropriately, but shut off later while running a game. Now it shuts off with that spark sound after running any program (browser, video player etc.) for a few minutes/seconds, and won't turn on afterwards (only LED blink and a "click"). Safe mode does't change a thing. Max temperature logged - 75 deg. Celsius. Last version of BIOS installed. Windows event log sometimes shows event 37 logged before shutoff. Something tells me it is a hardware issue.
Now - some weird stuff: 1) it can be "forced" to turn on by pressing "on/off" button while applying pressure on the center of the main circuit board region, and when pressure is released it often (not always) shuts off immediately with the same "spark" sound; 2) if it is running with external power supply while battery is inserted (usually I run it without battery) sometimes (rarely) instead of shutting off it would start to blink power LED indicator and "on/off" button LED like if battery was almost empty, and if during that blinking period adapter is rapidly disconnected and reconnected, laptop continues to work properly for some time, then issue repeats.
Stuff that I already did: 1) "static electricity release" (hold power button for 20 seconds or so while all power sources is disconnected) - no effect; 2) I disassembled it, cleaned it, looked for some obvious hardware faults like burnt resistors or damaged wire isolation (I know nothing about electronics, so...), and turned it on in disassembled state to try to spot sparks or jamming spinning parts and locate the source of that sound - issue persisted (shut off after starting a game), no visible sparks, spinning things are spinning, sound came from processor region (no visible damage on processor, all pins are straight and shiny)). Only thing that attracted my attention is that one of cooling system conductors was slightly bent away from its contact point, but it is not touching anything it should not touch. 3) I tried to run it with cooling system grounded - no effect.
I probably forgot something, but that's a lot of text already. I don't want to simply buy a new laptop, so I'm waiting for suggestions. And English is not my first language, so excuse me.