1) I dont know the different between an normal and clean installation.
2) Do you know the TI Nspire CAS without color? There is an tcc file with that you can install this "Old Boot Screen" From the old TI. The advantage is, that you TI will boot much faster because the old Boot screen dont loads the W-LAn Tasks etc. because the old TI had no W-LAN.
But i cant find that tcc file anymore, maybe somebody know what i mean
The shutting down seems to me like a bug .. i dont know my old TI CAS was on all the day, but never shuts down. After installing the new OS version nothing changed .. and the Akku i full. I mean the calculator works fine, but i hate it, when i let it for 5min and then i have to start it again .