Thanks for the replies.
As it was too painful to watch the little thing rebooting like crazy I just rest it to factory settings (and restored the original start.sh) right after I wrote this post.
What I was more interested in are ways to try and analyze (or some guess on) what was causing it.
(For the next time my kindle is in pain
)
@Yufan: after I reverted start.sh I noticed the private commands ~startIndexing and ~stopIndexing. My guess is you're the one who added them (I only used your hack + usbNetwork) as I remember reading they don't exist on the original firmware. (Or are they on 3.2.1?)
If it was really you who added them, may I ask what do you use to start and stop the indexing process?