Honestly, at this point I'd swap out the PSU with something different, even if there's no particular reason to be concerned about the PSU.
Your computer didn't necessarily break your monitor. Probably your monitor just died.Okay, so.
I just got myself a UPS - an APC Back-UPS Pro BN 1500VA.
APC Back-UPS Pro, 1500VA, Tower, 120V, 10 NEMA 5-15R outlets, LCD, 1 USB Type C + 1 USB Type A ports - BN1500M2 | APC USA
BN1500M2 - APC Back-UPS Pro, 1500VA, Tower, 120V, 10 NEMA 5-15R outlets, LCD, 1 USB Type C + 1 USB Type A ports | APC USAwww.apc.com
I tested my desktop on the UPS using both battery power and the standard surge protector. Both of them didn't work, which suggests that whatever issue my PC is having isn't the power after all.
More strangely, when both my monitor and my PC were connected to the UPS, the monitor also seemed to break after several tests. The model is an Acer s231HL
https://www.newegg.com/acer-s231hlbid-23/p/N82E16824009255
Now, whenever it's plugged in, the blue "on" light on the power button turns on, but the screen never connects, and I can't turn the monitor "off" - the light remains blue no matter how many times I press the power button to switch it off.
I've tested this with my laptop; this is purely an issue with the monitor now. The monitor does not connect to any device using any HDMI cable I have.
So, unless there's some really, really, really unfortunate timing here, something about my PC somehow broke my monitor too.
Any idea what's going on here?