Answer to "How to change battery for 750Li?"Independent BMW shop did registration for our car. They charged $50. Later I found that there is an app for iOS and Android that can do it for you. But, you will need to buy their OBDII adapter (connects via WiFi). If you will continue use BMWs, probably it is a good investment.
Answer to "Why won't ubuntu work?"Also, check this FAQ about installing Linux on PowerPC Macs, can be helpful: https://wiki.ubuntu.com/PowerPCFAQ