There is a lot of experience on this community, and 99% of the time you can get answers to your problems just by asking - but a little more detail is usually required. The community does not have a 140 character restriction like Twitter! ;-)
Just reading your post throws up a lot of questions....
Power Out when TX'ing? Radio front panel reporting low power? SWR Flashing? When tuning? When TX'ing?
More information on your setup, like the antenna, and whether it has been used before with no SWR issues on another radio would be helpful for all involved when trying to assist you with your problem. Are you using an external ATU, or did you opt for the built-in unit... etc etc
Anyway, welcome! We hope you love the 6300, you were one of the lucky ones who obviously ordered early.