TI Nspire CX CAS Stuck at bootup

Hello everybody,
Today i pressed the reset button on the back of my TI Nspire CX CAS. Since then it wont startup anymore. It is stuck on the gray screen with the clock cursor, which comes after the loading screen. I tried the maintenance menu. I tired every option. If i delete the OS in this menu, i can reinstall it but after the installation it is stuck on the same screen again.
I had the OS Version 4.0.235 installed.
Does anybody know a solution for this problem?
Im thankfully for every tipp.
Greetings
Today i pressed the reset button on the back of my TI Nspire CX CAS. Since then it wont startup anymore. It is stuck on the gray screen with the clock cursor, which comes after the loading screen. I tried the maintenance menu. I tired every option. If i delete the OS in this menu, i can reinstall it but after the installation it is stuck on the same screen again.
I had the OS Version 4.0.235 installed.
Does anybody know a solution for this problem?
Im thankfully for every tipp.
Greetings