There is some confusion possible when reading the replies, so here are the details :
flashing 88 can have 2 possible causes :
1. The original idea of the flashing 88 was to indicate that the RAM chip is defective. For that, the Behringer firmware writes to the RAM chip at startup, and reads back the data. If there is a difference, this indicates a RAM defect which is shown through a flashing "88" being displayed.
2. However there is a bug in the Behringer firmware : when a MIDI IN cable is connected, and MIDI data is being sent to the FCB1010 during startup, this data also ends up in the RAM and confuses the RAM test, resulting in a flashing "88".
Therefore, first thing to do is power on the FCB1010 with no cable connected to the MIDI IN. If you still have the flashing "88", it is a correct indication of a defective RAM, and the RAM chip needs to be replaced. This should preferably be done in a service centre, since it involves desoldering a small SMD device and soldering in the replacement part.
If you only have the flashing 88 with a MIDI cable connected to the MIDI IN connector, it's just the firmware bug. It can be avoided by always unplugging the MIDI cable during startup, or it can be solved by upgrading the firmware to UnO, which has this bug corrected. Replacing the firmware means swapping the PROM chip (not the RAM or EEPROM). This is easy and can be done by anyone - as correctly described above by Michael King.