Hi Andrea and welcome, you have the dreaded B200 bad, it can sometime be cancelled by removing the cartridges and powering on the printer to clear the error but you have tried that already, so there is no other magic bullet.
Worse, when a B200 is present it makes it impossible to remove the print head with the normal set of procedures and then there are no guarantees that if you do replace the print head that the B200 wont remain.
The procedure for head removal with the error present is far more difficult and it requires you to remover the top cover and several other bits to gain access to the print head, it’s a messy job and you’ll lose 40% of the ink you still have left in the cartridges.
Now a cheaper option would be to source a second hand Canon Pro 10 and use that for printing, because acquiring a new Pro 1 print head on EBay is not advisable, it may not be new but a refurbished print head instead. Only purchase from an official Canon agent..
If you still wish to proceed with your indeviour then PM me and I will give you the necessary information you need to safely dissemble the printer and safe head removal..