You can’t rebuild a new version of an apk from the apk itself.
Have the app developer do the following:
- Rebuild project in its previous state with higher version number (must be higher than all previously submitted versions)
- Resubmit
From Google’s Android “Developer Console” page:
Note that rollbacks aren’t supported due to the app versioning
requirements of the Android platform. If you need to rollback,
consider launching a previous APK with a new version number. However,
this practice should be used only as a last resort, as users will lose
access to new features and your old app may not be forward-compatible
with your server changes or data formats, so be sure to run alpha and
beta tests of your updates.