e60 Key remote battery? Need some input..

hello everyone,
Recently i had a dead battery in my 2005 525i. I left the lights on while i was doing some adjusting of the lights and hadnt even thought to turn the car on.
before the car died, the remote worked flawlessly
I jump started the car and now the remote key will barely work for me. I thought first that if it charged in the ignition for awhile it would recahrge and be all set. took the car for a 2 hour drive and its still dead

my next step is to replace the battery in the remote..?
a few questions..

Is this something i can do myself, or will a trip to the stealer be in my future..? ( new battery and re initialization?)
How much can i expect to spend to get this done if i cannot do it myself.

I have looked up and down and asked on another forum board to get no answers. The manual does not say how to re initialize or replace the battery.

attached is a pic of the key i have.

help! there is nothing more annoying than having full hands and having to set everything down on the ground to put the key in the door and unlock it hahaha

thanks!
-Bill