For a proprietary drive like the Big Disk, the easiest and probably the most cost effective thing to do is to buy another drive. Assuming that the circuit board dying hasn?t corrupted the data, you should be able to swap the drives out of the new unit and put your older drives in. If all is well, you will see your data. But if still there is any problem recovering your data then I will suggest you to go to data recovery labs. They will recover your data with a snatch of fingers. Few days ago my friend working in MNC came with a terror on his face. From him I came to know about how he has lost his data, with the system crash. He was supposed give very important information in his company. My friends and me tried our best to recover but failed. Then we decided to go to data recovery labs. The first lab, which we came across, didn?t work out well. Finally we reach SAlvageData Recovery Lab at Inc., 76 Progress Drive, Corporate Park, Stamford, CT 06902. Guess what it was just unexpected; he got all his data he had lost. Nice lab I must say. As you go to the lab you must tell them what exactly has happen i.e. how you have lost your data and what you did to recover it but failed etc. etc.
All the best.