have just installed my new HL-1210W wireless printer but it will not print, the red light keeps flashing.

Got it!
Have you already tried any ways to resolve the issue?

And could you specify, please, if the red light is flashing on the printer itself?

Got it, thank you for the information!
Tell me, please, do you see any error messages on the computer regarding your printer?

Could you tell me the way the red light is blinking, please? Is it blinking once in 1.5 seconds intervals or 4 times and turn off for 1 second?
Also, it may be blinking 3 times and turn off for 1 second

Okay! And the green button is turned off, right?

Is it blinking?

Appreciate the information!
Please, just to double-check, choose the most similar way for the lights blinking:

1. Both the green and red LEDs will turn on together, then the red LED will turn off after 0.5 seconds and the green LED will turn off after 1 second, they will then both be off for a further 1 second.
2. The red LED will blink 3 times at 0.5 second intervals and the green LED will light up. Then both LEDs will turn off for 1 second.

Could you specify, please, if you`ve printed something at least once after setting up the printer? Or have you never printed?

So you never printed using this printer, right?

I will do my best to help you, I just needed a bit more details to see the whole situation. Thank you for providing me with the details!
First, please, let`s try to perform a reset of the printer. To do this, follow these steps:

1. Turn off the printer by pressing and holding the "Power/Wi-Fi" button until the LED light turns off.
2. Wait for at least 5 seconds, then press and hold the "Power/Wi-Fi" button again until the LED light turns on.
3. Release the "Power/Wi-Fi" button once the LED light starts to blink.
4. Press and hold the "Power/Wi-Fi" button again until the LED light turns off and then turns back on.

Okay, no problem
Please, try the following, it should be for your model exactly this time:

• Turn the machine off.
• Make sure that the top cover is closed and the power cord is plugged in.

Now, please:

• While holding down the power button, open and close the top cover once.
• Release the power button. Make sure that all the LEDs turn off.
• Press the power button ten times. The machine will automatically restart

Okay, thank you for checking!
Let`s try to perform the factory reset and reset the printer to its default settings
To do these, please, follow these steps:

• Turn the machine off.
• Make sure that the top cover is closed and the power cord is plugged in.
• While holding down the power button, open and close the top cover once.
• Release the power button. Make sure that all the LEDs turn off.

Okay!
Now, please:

• Press the power button eight times. Make sure that all the LEDs light up to indicate the machine has been reset to its factory default settings. The machine will restart.

I see, thank you for checking that
Please, unplug the printer and open the front cover and check if something is stuck inside the printer.
Check for any torn pieces of paper or factory covers that may be obstructing the paper path.
Check the paper tray to make sure that the paper is properly loaded and not jammed.

At least we`ve found the source of the problem!
Is it stuck in the paper path?

Have you tried using a flashlight to get a better view of the paper and any areas where it may be stuck?

I see
Please, try to open the top cover and then slowly take out the drum unit and toner cartridge assembly. The jammed paper may be pulled out with the drum unit and toner cartridge assembly, or this may release the paper so you can pull it out from the inside of the machine

So have you pulled out the paper with the drum unit?

You mean the green light is off, right?

Okay!
Please, choose the way the red light is blinking:

1. will blink once in 1.5 seconds intervals.
2. will blink 4 times and turn off for 1 second.
3. will blink 3 times and turn off for 1 second.
4. will blink twice and turn off for 1 second.