Maybe the easiest way to know you are in flash mode is to start the rktool, it will say something about there not being an "rk.... something or the other connected". Switch off your tablet, connect it via usb, then do the whole volume up/power on thing. The line on rktool will change to something about "rk... found or connected". Sorry i don't have it in front of me. The screen stays off the whole time.
As for the fixing the wifi, I never really had any issuess with it, but I am on decon v3. I wouldn't have aclue what I was doing if I opened the unit to try and manually fix the antenna. Actually I do, I'd be wrecking it. But if you are confident enough let us know what happens.