Hi The blue indicates a notification i.e. a new email or message, so something may be working.
You may have to try your wife’s core module. Apparently the phone will work without all the smaller modules, so using your wife’s module won’t tell you much apart from as you discovered with the bottom module.
Now the warranty has definitely ‘gone’ you may open the bottom module to further clean and dry it. (As above]
Note however if the phone ‘should’ work without all the smaller modules then the only test for that is a charged battery.