Nas failure help fixing it and if not help with info of new nas

Evening All,

I've had my TVS-873 die, It keeps randomly shutting down and trying to reboot and get stuck on "System Booting" or "Loading Drivers". I have had this unit for a while and know it is out of warrintey.

It has 6x 4TB drives (in raid 6), 2x 1tb Nvme sata dives and 2x 500gb SSD for Cashe.

Have tried the following fixes to no avail :
Manage to update firmware no luck
Boot with no drives in very inconsistent if it will boot or not
Test different ram sticks tried 4 different sticks (memtesed and know working sticks)
Replace a Nvme Sata drive just to rebuild and test no luck

The only thing I think left to possibly try is replace the psu

Starting to run out of ideas if any one has any ideas on what to try next please let me know.

My other question If Im shit out of luck is if I buy a never Nas how easy is it to move across drives to rebuild and continue using the current setup / system

Im possibly looking at a
QNAP TS-h886-D1602-8G or
QNAP TVS-h874-i5-32G