Hi, I had this problem a couple of months back - ‘panic'‘ issue resulted in my laptop crashing intermittently.
All of the official Apple repair places I went to said that the logic board was defective, and that it was no longer possible to find a replacement as Apple had stopped making them in spite of acknowledging that they were defective between 2012 and 2014. Apple told me that the laptop was effectively bricked.
I did eventually find a solution which did not require my logic board to be replaced, and I have had a fully working laptop since.
For anyone in the UK, I really recommend these guys. The work cost £180 - much less than the £350+ to replace the logic board…if there were any available.
https://www.streamline-electronics.co.uk/
What I have been told (for others to verify), is that between 2012 and 2014, Apple used a solder for their chip boards that did not include lead. This meant that the solder melted at lower temperatures, and over time this caused faults to occur. The fix is therefore to replace the solder for the logic board, rather than replace the board itself.
It took me many hours of research to work this out, and so I hope that this message will help some of you to repair your laptops more quickly and at a lower cost. Good luck!