Controller is unreponsive

Good afternoon. Over the weekend we had a power outage. I'm fairly sure my controller didn't shut down gracefully as it has become completely unresponsive. My controller is the shelf mount and it is emitting a solid red light. I believe it usually has a flashing white light to indicate activity but I am getting nothing other than the constant red and I am getting nothing from HDMI either
Things I have tried
- disconnected everthing and left it overnight
- tried a new power supply
- tried different HDMI cables
- attempted a master image reinstall (tried  2 different USB drives and an SD Card) but nothing happened when I powered on. 

Any help would be much appreciated

Preventative - all computers should be on a UPS as no computer likes to be in a power cycle or worse, a brown out condition. And, that UPS should support NUTT software so myServer can monitor it and gracefully shut down when the power battery goes low.

Your shelf system should be a NVME internal drive - not a USB or SD card. If that is corrupt, you can try to apply the latest Master Image on that. You will need a USB to NVME adapter board to do this. It is also highly recommended to add the Master Image on a NEW NVME drive so you don't erase your system on the old NVME. Do you have a backup?

If the Pi has failed, you can try to reload it's firmware. You can research this on raspberry.org website.

You can also replace the Pi4 / 4 gig.

you say you tried a new power supply - hopefully it was properly rated for a Pi4 (3.5 amp or better). Most all phone chargers will not be enough power.

Look at the Pi (not the Shelf case LED) and advise what rhythm it is flashing at. This can point to a firmware problem.

Connect an HDMI monitor and wireless keyboard / mouse. Boot it...what shows on the screen? Any failure messages - especially when the boot stops? Take and post a screenshot here.

Hi David. I spent way too much time fixing this and not getting anywhere so I purchased a new Pi. That went incredibly smoothly and I now have my dashboard back bad news is I've lost everything. I'm trying to get my licence through configuration but I can't find myServer order number anywhere. Any way you can help?

Just enter "SmartRemoteKickstarter" as the order number. We have those records.
Did you also put the system on a compatible UPS? To prevent reoccurence.

Thanks David. My server is now attached to a UPS. I have connected the SSD from the old server to a windows laptop and this is what is on it. Is there anything there that might let me recover?

Will the old SSD boot the new Pi?
If no, can you boot the new Pi on a new Master image (download today's latest Trixie version) that is burned to a NEW, fast USB drive?
If you then post full boot (like 3 times boot), gracefully shut down, plug in the SSD and reboot...Hopefully that will boot from the new USB and the old myServer files can be migrated from old SSD to the new USB.
Then....apply the New Master image to the Old (or a new) SSD and boot from only that. Then transfer the files from New USB to New SSD. Restart and you have a pristine updated system.