If you've done it before it's easy. It looks like the port itself might be OK as it's recognising the charge cable. You'll have to open the screen. Then remove the lcd screws and the black gunk from around the lcd screw holes. Once that's done gently lift the lcd up and remove the screw from the battery connector. Insert something (very thin but stiff plastic usually works ok) between the battery and board connection to disconnect the battery. To check try turning the ipad on. If it doesn't come on then its disconnected and you can carry on. remove the screws from the plate covering the screen connections and lay them in the correct order then remove the plate. Disconect the digitiser and lcd connectors and lay them somewhere safe. Now you'll need to heat up the back of the ipad to soften the adhesive holding the battery in place. If you don't have access to a heat mat or hot air station you can use a hair dryer. Heat it until it's hot to the touch but not too hot. More very warm. Then I use a spudger to gently work on lifting the battery from the side. Gently inserting and lifting. Go slowly and take your time. Do this with both parts of the battery then when its free slide the spudger under the battery then under the motherboard to gently lift the board so you can lift the battery connector up and out. Once out clean the adhesive from the old battery and around the chassis then do the reverse to rebuild it. Make sure the battery seperater is in place so no power is in the board. Connect the digitiser and lcd and fit the plate and screws. Once on you can remove the separator and fit the battery screw. Turn it on to make sure it powers on then if OK refit the lcd screws and glue down the digitiser with some adhesive. Or you can buy replacement screen adhesives online. Hopefully this makes sense. Good luck 👍