I had the same problem! I checked the battery and it was dead. I charged it for about 15 minutes and I got the slides in. The trailer had been on shore power all summer but it didn't keep the battery charged so I must have a converter/charger problem. I have a 2014 Bighorn 35-85 and don't have a clue where the charger is located. I appreciate it if some one could clue me in. Good luck with yours.
1 - As stated, converter is behind basement wall.
2 - As you were plugged in all summer, have you checked the water level in battery?
3 - Did you flip all circuits off...then on again (inside trailer)? Sometime they look "on" but are really "off"
4 - Here is picture of the busbar. Look where I inserted the red arrows...that is probably where your reset button will be for the breaker.
5 - Do you have a voltmeter? You can test the converter by testing the voltage on the right side of the busbar (this time the white arrows). Make sure you've reset (on/off) all circuits first and you're then plugged into shore power.
6 - Any chance you have a battery cutoff switch, like I've circled in Blue and has blue arrow? If so, check that it is in the "on" position...you will see green behind selector. If you see red, it is off.