It sounds like your mosfet on your board burned out. I had the same thing happen recently and had to change my board out I also went ahead and put on a external mosfet for the bed and replaced the tined wires with ferrule connectors and have had no problems since. Here is the mosfet I put in https://www.amazon.com/dp/B07R292KXF/ref=cm_sw_r_cp_api_glt_fabc_H14GRR09WB8GA3PGGMSW?_encoding=UTF8&psc=1