It's been 5 years since I last worked on a Lexmark, we had some of the professional series for printing pharmacy pt data sheets for the prescriptions and the labels for them. They can be finicky and I remember the flashing as well.
Is yours flashing 12 times with no response from the printer? If yes this is an indication of the ink cartridge not being recognized as installed or simply not recognized as an OEM cartridge.
You can try to perform the diagnostics tests, the internal one in the printer and the printer cartridge(s).
To perform the printer diagnostics this is what I remember and your printer may be different and you may wish to refer to you manual or Lexmark's Troubleshooting site.
Switch the printer on and open the front cover of the printer. The cartridge carrier should move to the center of the opening remove both cartridges.
If the carrier does not move to the center of the opening, you will need to remove the cartridges by hand.
Turn the printer off and remove the power supply cable in the back of the printer. Open the front cover of the printer.
Inside the printer, locate the silver metal carrier bar on which the print carriage slides. Locate the black rubber carrier belt above the carrier bar. This belt has tracks on its inner portion.
Grab the top portion of the belt and move it toward the right. As you move this, the ink cartridge carrier will move to the left. Continue to move the belt until the carrier is in the center of the opening. Now pull both cartridges out.
To perform the self-test:
Disconnect both the power cable and the USB or parallel cable.
After one minute has passed, plug the power supply cable back in. Turn the printer off by pressing the green power button.
Hold down the paper feed button.
Turn the printer on by pressing the power button.
After the printer begins to feed paper, release the paper feed button.
Once the paper exits the printer, press the power button to turn the printer off.
If the power light blinks while no cartridges are installed, there is
a problem with the printer. If the paper went through the printer as if printing was occurring, you will need to do some more testing.
Test the ink cartridges:
Open the front cover and insert only the black ink cartridge. Close the front cover. If the light flashes there may be a defect in the black cartridge, if this is OEM return it for a refund, if aftermarket you might try removing the little chip from a used OEM, you can try this with the color cartridge just to ensure it does exactly what the black one did assuming it failed and if both do this I’d suspect the priter has bricked.