Can't start continual reboot sequence Mac mini 2019 Mac OS Monterey - Intel

Hi there,

I am having terrible trouble with a Mac mini Intel based. I'm pretty advanced with the general stuff and tried quite a few fixes to no avail.

Was having some problems with booting so conducted PRAM reset which fixed the problem, but its back.

start machine and did a PRAm reset, and now it just gets stuck in a restart loop, sometimes the apple logo comes up other times it chimes and restarts around 30 secs later.

Tried the following

PRAM reset

SMC reset

Disconnected peripherals one by one (except for the monitor HDMA)

Cmd R - nothing just rest

Shift safe mode - nothing

CMD S

Bootable USB for complete rebuild(Big Sur), I can get the two hard drives (SSD and Removable USB) to show but when I click in the USB it just restarts like before. USB 32GB SansDisk GUID apple formatted.

Tried to boot to terminal - no

One thing I noticed was that the SSD was very full and I have time machine backed up. I was about to remove a lot of files to reduce the size, but did not get to this before the reboot issues.

Any help you be amazing, thank you in advance

Michael