Hi karen, and welcome to justanswer.com, My name is ***** ***** I will do my best to assist you.
Most likely, all that needed to be replaced was the battery. It is possible that the DC input jack needed to be replaced, but with the technician telling you hed have to replace the screen as well, I dont put much faith in his diagnosis.
Here is my suggestion, get the ipad back from him. You may be out of the 49$ diagnostic fee but you are clearly being over charged for work that doesnt need to be done.
The most you should ever pay for this service is 99$ total. And thats if your ipad is over 1 year old. If its under a year old apple will repair it for free. Whether its over a year or under a year, the apple page below will help you get a free repair, or pay for the one time repair.
Apple always warranties their work as well. With that being said, you could replace the battery yourself and save some money. Considering the cost of the battery and the tools you need, it would run your about 50$ to replace it yourself. If you have any further questions or concerns, let me know!
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Senior Technician and Network Switching Systems Operator / Maintainer.