My 2.9 GHz 2016 MBP 15" CTO is on its 4th motherboard, with each failure being attributed to the SSD (1 TB). It was dropped off at a premier AASP for two repairs. On the first repair, the replacement MB failed on the service provider's workbench before returning the machine to me, so they had to order yet another one. Then within a year it failed again. Since then, it's been [deleted due to hardware related superstition].
It sounds like you'll ultimately have to suck it up and take it in for repair. If you need to get work done in your Mac environment immediately -- and you have a bootable clone, you could still operate your machine environment from the clone, or, better still, connect the clone volume to another relatively modern Mac, boot from there, and the environment will operate just like your original machine (then you wouldn't miss a beat while the machine is in repair).