It is a fat PS3 on OFW 4.82 and model CECHL03. I have an E3 flasher if that can do anything.
According to your 1st post, you can install fw in recovery mode, right?
Have you ever installed a CFW on this console at any point in the past?
If so, QA might already be enabled & you could install ofw 3.55 then use FSM to fix rsod permanently.
Otherwise, you could use the hardware flasher to downgrade to 3.55 then fix rsod under FSM.
I have never tried but in theory it might also be possible to use the hardware flasher with a no-fsm custom hex file to bypass rsod without downgrading.
I guess you would need to dump your nor, apply the no-fsm patch to the dump & apply another patch that replaces basic_plugins.sprx with a modded version that would bypass rsod temporarily. Then you could boot into 4.8x cfw & enter FSM (using CFW Settings) to reinitialise vtrm to fix rsod completely.
On CECH-L, the issue might come back though, even after a full vtrm fix. Hard to tell.
Check the rsod info on the wiki.
http://www.psdevwiki.com/ps3/RSOD_Fix