After around 2 minutes you should get the BED PREHEAT ERROR message on firmware 3.9.0 and upper or BED THERMAL RUNAWAY message on firmware lower than 3.9.0 displayed on the printer.

Set targeted temperatures back to 0°C via Preheat/Cooldown or Settings/Temperature menu.

Plug back the bed heater and let the hotend cool down under 50°C.

Turn the printer off after hotend and heated bed are cooled down.

If this step behaves differently please verify your connection and firmware. If it continues stop using your printer and contact us or ask for help.