Inside every Samsung toner cartridge (specifically the MLT-D104S model used by the ML-1665) is a small circuit board known as a CRUM (Customer Replaceable Unit Monitor) chip. This chip communicates with the printer, reporting the toner level and, crucially, the "life status" of the cartridge.
After the printer restarts, the firmware reset should have disabled the "End of Life" toner lock. Here is how to verify: samsung ml 1665 printer firmware reset