This has happened two separate times, correct?
Take a close look at where you are plugging into when you are packing up at home. You may have plugged into a faulty receptacle or adapter two separate times at your home. However, it seems unlikely because the adapter would also look melted or distorted and burnt. You said you were plugged into a wall. To me that means a 15 or 20-amp circuit and not likely to damage a stronger 30-amp male plug.
However, just to be safe, replace your 15 amp to 30-amp adapter. They cost $3.50 on Amazon. Buy two, keep a spare. Toss the old one into the trash.
click here to see part.No matter what has happened or where it happened, you still need to replace the blackened 30 amp “male NEMA TT-30P plug”. No need to replace the entire RV cord this time, just replace the male plug on the end of the cord from your RV. They cost $12.50 on Amazon. Buy two, carry a spare. Throw the old one away.
Camco 30-amp male mini….
Click here to see part.Other possible causes of your problem, however they are less likely but can’t be ruled out:
• Loose or burnt connections where cord connects to RV wall. If you have that type of connection
• Loose neutral (white wire) at your power center/ busbar.
• Loose wire at your 30-amp breaker inside your trailer.
• Bad breaker connection on the buss bar in the power center.
• Leaving your 30-amp cord in the weather to deteriorate and oxidize the copper connections.
• Bad luck at two separate camp grounds with bad receptacles at the post. This could happen.
• Driving a vehicle over your power cord, enough times to cause issues.
Unfortunately, you don’t give enough information to give a reasonable diagnosis. Post a few pictures.