Soldering with a delicate looking board
I actually can answer this, because I know the exact board he's talking about.  It probably looks very similar to this:



They are very simple, cheaply made PCBs.  One set of wires connects to a lion cell, the other end connects to the 510 threaded head (sometimes with 2 wires, other times one terminal is press fit or soldered right to the connector).

These boards are usually just a couple LEDs and a switch.  Some have a transistor to control the actual power so the switch doesn't die from arcing.

Soldering new wires to them isn't very difficult with a bit of practice.  Get a small vice or something to hold the board in place, then use desoldering wick or a solder sucker to remove the old wires and clean out the holes, insert new wires and solder them on.  The most important part is not to heat the board up too much - if you do, it will delaminate and the traces will lift off.

If you have a hard time getting the holes clean enough to insert the new wires, there are two tricks I have used before (after removing as much solder as possible, and getting the wires out:


Push a small thumbtack or needle into the hole while heating it up.  Twist the needle as the solder is cooling so it doesn't stick.
If that fails, use a tiny wire drill to drill the remaining solder out.