Hi William!
This could be a lot of things unfortunately. But it does sound like it’s having issues with the NAND or motherboard.
Since they are married to each other, it’s recommended to replace both of them (as set).
You CAN try to replace the NAND (small IC connected to the motherboard), but then you do need to re-programm, reflash it to make it work.
Please let me know what you want to try for yourself, then I can sent you some guides!