I'm sorry I didn't read this question until today.

Anyway the 1998 Chevy K1500 is a different system than this older PATS design. Your system has a learning feature and by following the relearn procedure, it will relearn the key or New Key/Lock cylinder you are installing. I have run into only one problem over the years that does not allow the relearn to "Start". It is because the plastic switch mounted in the housing above the lock cylinder is worn or broken off and does not register the key is inserted. It is a simple on/off switch and can be tested mounted in the housing or remover, but removing the switch can give you a false positive test because the button may be wore enough to prevent the key from pressing upward enough to open the contacts.

The switch is small, white, two wire and located in the ignition key housing, directly above the key. It was to be rotated to removed. In that housing you'll see three wires plugged in and the white switch to the right and in. I don't see any way to post pictures.

Once you get the two edges of the SIM card and SD Card trays popped up you can easily remove the cover using a small pocket screwdriver by putting the screwdriver blade sideways in the groove between the cover and bottom case. Then slide the small edge of the blade foreword in the groove between the cover and case popping it open as the larger part of the blade spreads it apart. Be sure to go all the way around. Do not attempt to pull open the case once you can get your fingers under it. Do not push the screwdriver directly inside the case. Sliding along the case it should only be in a groove about 0.030” or .75mm deep and it will work like a zipper.

The battery four wire connector lifts straight up. Gently pry up from under the wire end using the iFixit tool #IF145-335-2 or similar tool. Reinstall it by aligning it over the top and pressing straight back down. Check it lays flat using the same tool.

There is a small amount of adhesive all around the screen holding it to the frame. You may not need extra adhesive to complete the job but you should have some ready, just in case. Remove the screen from the frame by holding the edges of the case with your fingers and gently pushing on the metal part of the screen sort of peeling the frame off the screen working your way all the way around.

Don’t remove that small board in the middle picture. No need to remove the two screws mounting it either. Just take care removing the ribbon cable from that board. Also the antenna cable lifts straight up. Use very light prying action with a plastic prying tool such as the iFixit Opening tool #IF145-335-2. When reinstalling the antenna, align it straight over the top of the post and press down using the same tool.