This is how I did mine.
Get two preferably different coloured wires about a metre long with a female spade connector on one end of each wire.
Make sure the Handbrake is ON before you start.
Before touching the brake calipers, pads, etc : open the cable connector plug at the back of the caliper and fit the spade connector ends of the wires inside the connector. Touch the other ends of the wires to the spare battery and if nothing (or very little) happens then swap the battery terminals.
You should hear it winding out for a few seconds then as soon as it stops release the wires from the battery.
You can then remove the spade connectors from the back of the caliper, reconnect the connector plug and carry on as per the old days to remove the pads, disc, etc.
Repeat the process on the other wheel. Once it is all buttoned back up you can use the EPB button to reset the pistons
Connect one wire to one side of the spare car battery or 9v lamp battery. (9v fire alarm battery may work too). Touch and hold the 2nd wire to the other end of battery. If nothing happens reverse the connectors. If it starts whirring away keep cables connected until it stops and then immediately cut the current.
NOTE: This method, like when using VIDA or the official Volvo method (as shown in the above video), only retracts the parking brake screw internally - you still need to lever the piston back into the caliper, separately, to change the pads.
More discussions here:
https://www.volvoforums.org.uk/showthread.php?t=282093