On the Teensy, there are two GND holes and two VCC holes -- you destroyed both?
You can get the 5V from the big pad in the back near where it says "5V" and also the "middle" one. Also there's an even bigger pad next to it, where the 3.3v voltage regulator would normally go). Just look at the trace to know which one I am talking about. Also you can use the multimeter (continuity test I mean) to be sure. You can also hook directly to the USB wire 5V -- it is all connected. There are other spots on the board (Like there are 5 1uf capacitor connected to VCC, but these are tiny and then you run the risk of unsoldering them).
Trick to solder to a pad:
1- Fill the pad with solder. (no wire here, just the pad alone)
2- Put solder on the wire. (separately)
3- Then hold the wire on the pad and just apply heat.
This will essentially "re-heat" the solder and make one big solder blob. Jobs done!
If your iron is very hot, it will eventually lift the pads. So if this is your case, do not leave the iron for "too long". I know this is pretty vague timing description, but I have nothing better to say.
The trick above will help on that regard, it should be quick.
Another trick: Often the pads (or wire) are not accepting the solder right away and/or it appears to be difficult to transfer the heat to the pad/wire. Flux would be the answer for this, but I suppose you do not have a bottle of flux around. One way to transfer "heat" is to use solder itself (since it is in a liquid form) -- and always use "fresh" solder since it contains a bit of flux in its core (flux eventually goes away after heating). So put new solder on the iron and touch the pad with the solder to make a better contact than your "solid" iron. DISCLAIMER: everybody will tell you to heat the metal not the solder. But this is a case where the metal or the iron is not making good contact and we just want to jumpstart the soldering and make a better heat transfer. Once you did that once to the metal it becomes "easier" to solder.
Another thing: Also it is good if you can have a wet soft "pad" (like a sponge) where you can cleanup your iron tip. The water will avoid the burning of the pad/sponge (do not hold with your fingers!).