So definitive answer you are looking for:
Bad news first:
I am by law not obligated to give any refunds for customer specific equipment like the bitburners as stated in my AGB (Terms of Service).
Comment on this: The Bitburner is, to be honest, not an individually designed, non otherwise sellable product and this might not hold in german courts. Prepare some money for the crazies...
It is a custom made PCB....