By putting the wrong position chip on your LLK refill cartridge, you confused the printer, so it is now displaying a maintenance tank error and won't open the cartridge bay door. It is common for the printer to display an error with the maintenance tank when you attach the wrong position chip to a cartridge, your maintenance tank is fine. To correct this, Kelly has tested a new LLK reset chip in our 3800 printer to verify it works correctly, and it's already on the way to you in the mail.
To open the locked cartridge bay door, you can gently pull on the bottom/front edge of the door and it will pop open. To correct the chip error, you will need to place the Epson LLK chip under the new LLK reset chip when it arrives, and your printer should recognize it correctly like the others, and display the correct reading of your maintenance tank.
Please let me know if you have further questions or there's anything else we can help you with.
Best regards~ Dana