You can disassemble an eGo
if they don't require you to return it for warranty credit (check first) but it involves removing the
threaded end, which is pressed into the top. If you remove the threaded end (the best way), you may have to find a pipe fitting that matches the thread size of the cone threads and use a pipe nipple with the female adapter that fits the cone threads. Use the pipe as a lever to wiggle it until the cement gives away. The electronics are attached to the end cap and the battery is soldered via wires and will come out with the threaded end cap along with a couple of pieces of foam padding that keeps the battery from banging around inside.
There's little way to repair it unless you can get the parts.
batteries are consumables and if you are lucky, you supplier will honor a 30 day battery guarantee.