3 Answers

That happened to mine, too, and I really thought it was ready for the trash; then, one day it finally worked again.  I can't explain it. 
My phone also stopped taking a charge, even with the original charger cord.  Turned out the connection was shot in the phone itself...I had to replace the phone.  $$$$$$$$$$$$$$$$$$

If you can't fix it with the advice ROMOS gave you, take it to the place who provides your service and have them make a valiant effort or recommend a repair spot. I have mixed success with The Geek Squad.

Check here...https://www.apple.com/uk/support/ipad/repair/battery-power/

Brand SeikoModel SRPK43 and SSC923Diameter 45mm SRPK43 41.4mm SSC923Thickness 13.2mm SRPK43 13mmSSC923Case Material Stainless steel hard coating with ceramic bezel bothDial Color Grey-blackIndexes Lumed hours lume pip on link the diverLume LumiBrite on hands indexes and bezelWater Resistance 200m SRPK43 100m SSC923StrapBracelet Stainless steel hard coating link with 22mm lug width SRPK43 Nylon with 21mm lug width link SSC923