I've kept notes of trouble shooting suggestions from other users for when I run into problems. When mine did this it was both of the selonoids under your feet. They control the boom, bucket and a third one on top is for the auxiliary hydraulics. Look at the dash when you get in. Does the seat and seat belt light go out? When you rock the parking brake does park and hydraulic lock go off? Good luck.
I'm assuming your skid steer is stock. Is your bucket also locked out? The multiple lockouts to release the boom/bucket include the seat, seat belt and parking brake lockouts. It also includes a door switch lockout if you have a door. Did you check the interlock fuse? It's F4. Did you check your seat/seat belt fuse? It's F2. If either is blown, you likely have a wire that has rubbed through the insulation and grounding.
Your door switch will be normally open or closed depending on the switch location (front or rear mount). When the key switch is in the run or start position and the park brake switch is in the RUN (middle detent) position, the instrument cluster provides ground for the bucket lock solenoid and boom lock solenoids (two) through wires from the instrument cluster. The ground circuit is completed through the instrument cluster wire 128 (black) allowing the solenoids to energize.
Are you handy with an electrical multimeter? If so, the seat switch, seat belt switch and door switch are simple two wire switches and can be tested using resistance. The instrument cluster provides grounds to complete the lockout circuit. The boom and bucket solenoids get their ground from terminal X7 (purple/black wire) on the instrument panel.
Your machine technical manual is readily available on the internet and has excellent troubleshooting sections in it, step-by-step.
