The red light is blinking and it doesn't print.

There are actually some certain meaning on the red light and green light showing different information to user. The summaries are:
1) Green On, Red Off = Printer Ready.
2) Green Fast-Flashing, Red Fast-Flashing = Printer warm up.
3) Green Fast-Flashing, Red Off = Printer off-line.
4) Green Slow-Flashing, Red Off = Processing Data.
5) Green Off, Red On = Cover Opened, Toner Empty or Developer Unit / Drum unit missing.
6) Green Off, Red Fast-Flashing = Paper Jam or waiting for jam reset.
7) Green Off, Red Slow-Flashing = Paper Empty or Paper tray is not inserted.
8) Green Off, Red Off = Printer power is off.
9) Green Very-Slow-Flashing, Red Off = Printer in sleep mode.
10) Green (any condition above), Red Slow-Flashing = Toner low or paper empty.

So what is your printer condition? Better know what is going on your printer so can solve the problem.

A red blinking light means error. It could be as simple as a jammed piece of paper. To the fact that your fuser section has not reach the correct temperature. Or a toner or cartridge issue. Keep it simple.

GT-1500 Scanner not Scan
When power on after attach USB cable then fast red light blink
what may be problem?