Unable to switch off Prime 4 Controller after firmware upgrade

I upgraded Prime 4 firmware from 1.6 to 2.1 and the unit is stuck saying it is upgrading database of Prime 4 SSD (Internal) and cannot be switched off. I have had the unit doing this for the last 24 hours. It seems the only way of turning it off is to pull the plug, but this will not be the best for the unit. Any help with this appreciated.

Try doing what this guy posted if you are able to?

@JustMe, thanks. In the end, I just removed the SSD and restarted it and it working fine now. However, I will have to reformat my hard drive and restore my backup. It’s a lot of hassle I really could have done without. But thanks anyway for your help.