Possible broken firmware HDS721050CLA362

Hi, I have this disk from many years. Suddenly it did not work anymore, without any noise, only don’t work ( no spinning noise, bios don’t recognise it) Thinking on a electronic fail, I bought an identical disk (same model, same firmware) and I tried this: (where A is my old broken disk and B is the new disk)
-swapping logical board: disk A spin but don’t work;disk B nothing work;

  • swapping bios chip ( the eeprom , eprom, nwram… I don’t know… the chip is 25U206A): disk A with B board and chip A don’t work, disk A with board A and B chip, spin but don’t work; disk B with board A and chip B it’s OK! So the A board is good and only the bios chip fail. It’s possible to repair?

I hope I explained myself. Thank you all

ehm… why do you have deleted my HD model name?

Hi Giulio_laconcig,

I think you have done Lots of R&D with your hard disk, hope your data remains safe. If data is important for you then first take backup of your data and then try combination of doing R&D with boards and chip. For taking backup of your data you may consult any data recovery company because your hard drive stops working.