xbox controller blinking

The controller will also stop blinking as if it's connected then start to blink again.

Ok, so does that mean I have to "re-pair" the controller with an Xbox first and that's why it isn't blinking on its own? That would mean the controller is working perfectly fine and it's normal that it doesn't blink when pressing the Xbox button after using
it on a pc?

Press the pairing button on your controller: On your controller, there is a pairing button (usually on the bottom of the controller, near the Xbox button). Press and hold this button until the LED on your controller starts blinking.

Wait for it to pair: The LED on your controller should stop blinking and turn one of four colors, indicating that the pairing was successful.

As this can caused by multiple things, a good idea is to follow this troubleshooting procedure.

First, get a Micro-USB cable (make sure it's a data cable, and not just a phone charging cable, as these often lack the USB data lines and only provide power).

Remove the batteries from the controller (to make sure it's not a battery issue).

With the Micro USB data cable, connect the cable to a free USB port on your Xbox console and the controller.

Does the controller work? If not, the controller is probably defective. The controller will transmit controller data to the console via USB cable.

If it does work, unplug the USB cable and find a USB power adapter (like a phone charger) and connect the controller to the power source with the Micro USB cable. That way the controller will have to use it's wireless radio to transmit controller signals.
If the controller is blinking, it's not properly synced and you need to press the bind button on the controller (the small button between the LB and RB buttons) and the bind button on the console (on the original Xbox One it's the button on the left side of
the disc slot, and on the One S and X models it's the small button near the power button).

If the controller properly works with the USB power adapter, remove the USB cable and insert your batteries. If the controller is now blinking, your batteries can't hold enough charge anymore and need to be replaced.

You might be having sync issues. If batteries are no problem, then I usually pull out the batteries, plug them back in and turn the controller back on. I’ll attempt a resync with the console and hope it sticks. Sometimes if at a certain angle, your console
might lose the IR signal from the controllers line of sight.