The HTC Desire 601 back cover should only be removed to access the battery, SIM card slot or SD card slot. To avoid damage, it is very important to remove and attach the back cover properly. Follow these steps to remove or attach the back cover:

1. Remove the back cover.
2. With the bottom panel facing you, pry open the back cover from the notch near the charger/accessory jack.
3. Gently pull the back cover from the bottom and sides of the phone.
4. Reinstall the back cover.
5. Align the top part of the back cover with the phone, and then press the sides and the bottom part of the cover until it locks into place.
   Make sure that there are no gaps or bulges along the sides.