!!
critical Brother
Error Code Ready - Green LED (blinking)
Service call required.
? What Causes This
A serious hardware malfunction or error has been detected.
✓ How to Fix It
Contact Brother customer service or a qualified technician for assistance. See User's Guide Chapter 6.
Source: page 5 of the official manual
From the manual
This error code appears in:
Brother HL-2000 Monochrome Laser Printer