I have not seen any issues... Though I would have contacted Samsung right away about the issue, before modding.
Rule of thumb never mod a new device that has issues with functionality get it fixed first and foremost.
Un-root and send it in. All my roots installed or removed will properly perform the firmware update function both in Kies and in settings.
If anything you can install an OEM firmware from sammobile and give samsung a fresh clean tablet to fix.
If you should see any wifi connection points listed in your wifi settings. Your wifi is at least picking up signals.
You can try editing the build.prop to allow 13 or 14 channels in Wifi if you are outside of the US. Or use ACE wifi fixer from the app store.