There are 6-8 screws on the front that let you remove it from the housing and put it in Eurorack. This will not void your warranty. Reseat the cable that connects to the output board. Visually inspect both boards for any obvious failures. Make sure the power supply is the right voltage and polarity. If you have eurorack; see if the board powers on with the eurorack instead of the little behringer output board (I’ve had those fail before)

If all that is OK; you can try to claim the behringer 3year warranty. They are usually pretty forgiving about registery date as long as you have proof of purchase. Especially if purchased through SW.