Troubleshooting How to replace the battery of Philips Touch-up pen trimmer To replace the battery of your Philips Touch-up pen trimmer, please follow our simple instructions below. Open the battery compartment Turn the lower part of the trimmer anti-clockwise to open the battery compartment. Replace the battery Remove the empty battery and insert the new one. Make sure the plus pole goes in first. Close the battery compartment Place the battery cap back on the trimmer and turn it clockwise to close the battery compartment.