Locking/breaking a 300v brushless DC motor for encoder calibration

Hi how’s it going, I was wondering if someone with a bit more knowledge on 3 phase brushless DC motors could help me out with “locking” my motor? See I’m getting ready to remove the hall sensor on a 300v DC spindle motor from out of a CNC mill and upgrade it to use an encoder instead. The end result is to turn the motor into a servo for more precise speed and even be able to use the spindle to do tapping operations. Part of installing the encoder is that the motor must be locked or more like the phase 1 wire be energized and the phase 2 wire be grounded but leaving the phase 3 wire completely disconnected. This should make the motor rotate to a fixed angle and be locked. Then with the motor locked I'm suppose to send the encoder the zero command which will tell it to store the position the motors at as zero and save it in its non-volatile memory.

What I’m wondering is since I’m doing this all at home and only have the skills of a hobby enthusiast is it going to be ok to use a 4S (14.8V) battery to energize the two wires on the motor and lock it or am I risking burning the pole windings up on the 300V BLDC motor? Or would be the opposite and 14.8V even be enough to move the motor at all? See I don’t have a variable power supply to work with or anything here at my place. I just don’t want to burn the motor windings up or anything.

Anyways if someone could confirm hooking a 4s(14.8v) lipo battery up to a 300V BLDC motor is a good idea to lock it? Thanks