First thought is a bad cord and you've got excellent advice above. Consider trying another site, see below.
50A is 12,000 watts which is a lot of power and cutting the cord likely caused a short resulting in high transient voltages and currents until the pedestal CB tripped. This can cause damage to the CG power or to your RV and now your GFI trips.
You should give serious consideration to having your RV checked by a good "electrician" because repair can be expensive and for peace of mind.
From your description the CG is a parts replacer and that diagnostic approach can be time consuming and expensive.