You already have tried most of my prior suggestions to fix this issue.
There has been one other unresolved case of this recently 
The only other thing I can think to try would be to use the button in Diag Tool > Advanced to go back to 2.3.7.146, after it reboots if still stuck do another soft reset. The other user tried to go back to 2.3.7 (without using that special button) but still was stuck so it may not work.
Other than that you would have to send a PM to @support_team or wait for someone to respond here. Just keep your backups safe and once they can get it un-stuck you should be back in business with a backup.
