Does the microwave oven come on?
It is not uncommon for mistakes to be made at the battery installation. Be certain the polarity is correct and that every one of the multiple cables is properly connected. Do you have a photo of the batteries when they were last properly connected?
Are these new batteries? If old ones, why were they removed?
You said, “ I don't even have electric current from my 30 Amp cord working anything.”, but also said, “ I have no power--no lights, no frig, no slides, nothing except one outside receptacle.”. Please clarify. Does the outside receptacle have 120 volt AC present or not, or are you talking about a 12 volt DC receptacle?
Are these lead acid batteries? Reading 14.4 volts DC on a 12 volt lead acid battery will only happen if an active charger or alternator is connected. Otherwise, expect more like 12.6 volts.
2020 Sunseeker 2440DS on 2019 Ford E-450, Trekker cap, Topaz paint