Burned power distribution box

[Mistercamp]

Anyone have this happen before? Had on and off battery discharged warnings. Replaced FRM a couple months ago which seemed to fix it. But the last week was getting battery discharged warnings again. Then last night went to the store, came back, car wouldn't start. Found the image below. No blown fuses anywhere which I find odd if there was such a draw to cause melting. Plan on checking the wiring from battery to the b terminal to starter/alternator. I did have aftermarket trailer light module and inverter, but both had been disconnected prior to this. Just curious if someone else here had seen this. 2010 35d.