Make and model UPSs? Age, condition?
How is everything connected?
Do you have for example, the HOME UPS providing power to the PC UPS in some manner? Often referred to as a "daisy chain".
Daisy chaining UPSs and adding in other components (surge protectors) is not recommended. Check the applicable User Guides/Manuals for the UPS's regarding supported configurations.
Any other surge protectors, power bars, use of multiple wall outlets? If you have, for example, connected some other devices such as a laser printer then the UPS is not going to provide backup power for very long and then all suddenly gets shut down. Only critical devices should be connected to a UPS. For me that is the computer and the monitor. The objective is to have power just long enough to gracefully and properly shutdown the computer. Not continue gaming, browsing, working, etc...
There are other concerns as well.
If the connections form an electrical loop of any kind where device A connects to B connects to C connects to D and then connects to A again then that is a loop that can and does cause problems. Loops being electrical, video, or audio. Especially if there are low end quality power bars, surge protectors, extension cords, and so forth being used. Especially those of the kind found in the big box store bins or online - low quality, cheap, and limited in use.
Indeed, sudden power losses can corrupt files and thus the system will not boot or otherwise not function as it should.
You may well have three sets of problems:
1) Being three years old that DeepCool PSU may be starting to falter and fail. Especially if it has a history of heavy use for gaming plus being exposed to external power fluctuations.
2) The UPS provided backup power may not be truly working because of the way the UPS connections are made. Or the age and condition of the UPS's/batteries themselves. And the UPSs' may offer some sort or surge protection (Joules) but that protection is limited. After so many "hits" there is no longer any protection.
3) The sudden power losses (despite having UPSs present) likely caused corrupted files.
The first objective is to get your pc working again. Isolate the pc as best you can from any potential electrical problems. Swap in a known working PSU and see if the system will boot. Even if only into Safe Mode. Then try "sfc /scannow" and "dism".
However, it may be that a clean windows install will be necessary:
FYI:
https://forums.tomshardware.com/faq/windows-10-clean-install-tutorial.3170366
Once the computer is working again then, focus on how to set up and configure a working UPS environment to protect the computer from surges and provide backup power long enough to properly shut down the computer via the power icon - not by using any physical switches.
Then take a closer look at the overall electrical system: Home UPS, personal computer UPS, and how it is all connected and configured. Read the applicable User Guides/Manuals and if necessary get a qualified electrician to help. You may have overloaded circuits, improper grounding/earthing, etc. possibly contributing to the overall problems.