Error code 5b02 might or might not mean ink absorber full. Here is a list in German of Canon error codes. Here is a clip:
5b00/5b01 means the ink absorber is full. 5b02 - 5b15 is a general printer problem which could mean any anything. It is suggested to pull and reconnect the mains cable.
IF the 5b02 means ink absorber full, then service tool v6220 is claimed by the seller to support your printer.
Googling Canon TR4540 error 5b02 finds a lot of different explanations, so what is true? Sadly there is no service manual to be found for your printer.