Performed a screen replacement, now the wifi is greyed out

I was fixing an iPhone 4S screen for someone and I was very careful whilst doing so (I have the correct tools etc.) and after fixing it they say that their wifi isn't working, the option to turn it on is greyed out.

I told them to try turning on airplane mode, turning off the phone for 10 minutes, then turning it back on and turning airplane mode back off - supposedly that works, but it didn't.

The next step was to try resetting the network settings and that didn't work either.

So currently they're restoring their phone, could this possibly work or is there another cause to it, maybe regarding hardware?