This error per the Epson service manual on page 67 means:
NOTE : Ex): When "Maintenance Request 0088" is displayed. As "0088" in hexadecimal means "1000 1000" in binary, you can find out the code is assigned to Bit-3 and Bit-7 referring to the above table. In this case, two errors are occurring simultaneously. (Bit-3: battery exhaustion/ Bit-7: the date and time has not been set.)
So three questions arrise:
1) Where is the battery located?
2) What kind of battery is required?
3) How to set the RTC to augment date and time.