Start by switching off your phone.

Heat an iOpener and apply it to the back cover to soften the adhesive.

The adhesive of the Samsung Galaxy A50 is very strong. A hair dryer, heat gun, or hot plate may also be used if you aren't able to open the device with the iOpener. Be careful not to overheat the phone—the AMOLED display and internal battery are both susceptible to heat damage.