doesn't have power

Bocs Endaya you want to start by making sure you are charging the battery. Check your charger to make sure it has proper output. Next, check your charging cable. Make sure that the ends are ok and no bend pins or debris in it. After that, check your charge connector. Same here, make sure the are no bend pins, corrosion or debris. Use a USB ammeter and check to see how many amps your phone pulls. If it does "pull" proper amperage but does not hold a charge, you want to replace the battery. If it does not, you need to check the charge connector. After that you will need to check your board. Use the Samsung flowchart

to go step-by-step

Use the component layout and your PDF readers search function, to locate the components to check J5 Component Layout

To work on your phone use something like this video