(Unknown Malfunction) Mobo refuses to connect to monitors directly and through GPU's

Speedwagon1936

Known specs:

Base GPU: MSI NVIDIA GTX 1660 Ti Ventus XS 6G OC

Base Motherboard: MSI B450 Tomahawk

All I did for this one was take the cooler out to replace the dried thermal paste on the CPU and didn't touch anything else besides lightly dusting it with my air gun.

I booted it back up to test it and now everything turns on but neither the motherboard or GPU will connect to any monitor. The VGA light is on though but everything was working perfectly fine before this with performance testing. Even with the GPU removed and an additional CPU/RAM tested the light persists along with the lack of any display.

I already reset the CMOS & tried replacing its battery, used multiple monitors and HDMI cords, swapped all the cords two times, used a spare and moved the GPU to another slot too. The GPU and other components run fine on any other motherboard I tested them on and the spare itself is functional giving the same results on the effected moba.

I have exhausted a full week traveling to other techs in my network and searching the internet asking for answers on this just to find others with the same unsolved issue with the B450 moba in particular and one other that is irrelevant that shared this issue.

It remains a mystery on what is particularly causing this issue and I have no explanation for the customer on how it even occurred in the first place.