Signature ( Certificate) Problem on Google Play while uploading a new Version of my app.

[Der Denker]

Hello everyone,

I am an AI enthousiast.
In 2015 i released an Application, designed on AI. Now i have made some change in my App unsing AI2 on the Amazon Server this time ( for bigger Apps), using the aia file of my App Project from the MIT AI2 Server.

I went back to the MIT  AI2 Server to download the Keystore of the App that i then uploaded on A2M.
I didnt generate a new Keystore file, just filed the path and saved the configs(androidKey for alias and android for pass), even signing and aligning worked, but there is still a signature problem on Google Play while Uploadind the Version.

My other problem is that i am not sure if i effectively deleted that App project from MIT AI2 Server years ago and recreated the same Project from scratch, meaning that the certificate would change definitively. But if that is the case how would i know??? maybe i deleted only one screen of the app and recreated it aftewards but not the whole app project, i dont remember.

Many people downloaded the last Version so i want to upload a new version so that they would be notified.

1) How can i solve this certificate problem with my new version??? suposing that i never deleted the original project from MIT AI2 Server, even thou their Keystore doesnt work on Google Play

2) If i had indeed deleted my original MIT AI2 project and then recreated the same app there from scratch again, clearly the Keystore wont work on Google Play. What can i do now???

3) Can i reverse Engineered my old existing app version on Google play to take there the problematic certicate and sign my new version with it to upload???? if yes how

PLEASE HELP ME
SCREENSHOT IN GERMAN

Hochladen fehlgeschlagen

Du hast eine APK-Datei hochgeladen, die mit einem anderen Zertifikat signiert ist als deine vorherigen APK-Dateien. Es muss dasselbe Zertifikat verwendet werden. Deine vorhandenen APK-Dateien sind mit folgenden Zertifikaten und ID-Dateien signiert:

[ SHA1: 5A:FC:3F:A4:74:59:7D:FE:ED:20:AC:A1:08:CF:25:30:BC:91:E9:24 ]       (OLD CERTIFICATE!!!!!)

. Die Zertifikate, mit denen die hochgeladene APK-Datei signiert ist, weisen die ID-Dateien

[ SHA1: 23:66:52:1B:C5:84:B2:1D:82:25:BC:C6:CE:1C:2C:81:B4:4F:7A:86 ]        ( NEW CERTIFICATE!!!!)

auf.