Based on what… the drive is utterly destroyed? Some shows are unwatchable while others are fine? If older recordings are fine, the assumption of utter destruction may be premature.
Me, I’d put the internal dive back and see, if you already think it may be lost… it’s not like you can make it worse than destroyed.
The DB info is stored internally on the tablo. Nightly maintenance mode should clean this up… if you want to put the first drive back – do not leave you tablo powered up overnight and loose this info!! Once you loose this, you’ll have a real PITA to recover your good recordings.
There is hope. One thing you really may want to consider – https://www.tablotv.com/ask-tablo/ contact tech support and get personal 1:1 real-time support (yea, their hours are pathetic) if possible.
For some users, the heat is a perceived issues as there are several post from tablotv and tablo support units do get hot and it’s “ok”, or it will shut down.