Is it possible to unbrick an nspire cx model P with ttl

→ **MyCalcs** profile · by **papuSpartan** » 10 Mar 2020, 21:49

I have a model P and i can no longer install the version that it was using

I upgraded to a newer version earlier this year due to it having issues booting. Trying to install version 4.4.0 gives error M7,

you cannot install an os which version is older than what is currently installed.

(The version shows 0.0.0 in computer link)

→ **MyCalcs** profile · by **Hamza.S** » 10 Mar 2020, 22:28

critor wrote:(23:45:48) critor: @papuSpartan replace "current version" by "highest version ever installed" in the message
(23:46:27) critor: if you updated to version 4.5.1+ just once, then there is currently no going back

→ **MyCalcs** profile · by **critor** » 10 Mar 2020, 22:31

Try to install version 4.5.0.
If if gets rejected too with the same error message, then you'll have to reinstall version 4.5.1 or 4.5.2. There is currently no way to reinstall older versions in this case.

→ **MyCalcs** profile · by **papuSpartan** » 10 Mar 2020, 23:04

4.5.0 failed to install and 4.5.1 succeded. I would like to clear up the fact that I am installing the CAS versions of the os and not the nonCas cx versions. The software will not allow me to install cx software because it sees my calculator as a CAS model. Anyways, after 4.5.1 CAS succeeded it is now frozen at about 10% on the cx loading screen.

→ **MyCalcs** profile · by **critor** » 10 Mar 2020, 23:09

Thanks.

Do you remember which tool you did install to make your calculator accept CAS OSes ?
nBoot+ControlX or nLoader ?

→ **MyCalcs** profile · by **papuSpartan** » 10 Mar 2020, 23:10

Well I tried resetting and now I just get a red screen...

→ **MyCalcs** profile · by **papuSpartan** » 10 Mar 2020, 23:13

critor wrote:Thanks.

Do you remember which tool you did install to make your calculator accept CAS OSes ?
nBoot+ControlX or nLoader ?

I Think maybe it was the former but I can't see the files in my calculator now. I was able to see them earlier when it was in "install os" mode. Maybe I should wipe os to check the files inside?

→ **MyCalcs** profile · by **critor** » 10 Mar 2020, 23:15

papuSpartan wrote:Well I tried resetting and now I just get a red screen...

It's probably nLoader then.
Unfortunately nLoader doesn't support versions 4.5.1+, hence the red screen.

If you did follow our nLoader how-to thoroughly, you should be able to bypass nLoader by holding

while pressing and releasing the reset button.
You should then be able to install a working non-CAS 4.5.1+ version.

→ **MyCalcs** profile · by **papuSpartan** » 10 Mar 2020, 23:32

I did as you say and I was able to fully install OS 4.5.1 nonCas cx. On reboot however, I still get the same annoying "calc has been modded for use with CAS its use is not permitted etc etc";So, I tried bypassing nLoader again to see if that would get it to the normal OS but to no avail, it now wants me to install it yet again. So without bypassing nLoader the computer sees the calc as being a CAS model and after bypassing it I can install it because it sees it as a cx model but then I cannot boot into the OS.

→ **MyCalcs** profile · by **critor** » 10 Mar 2020, 23:41

Ok, thanks. It's nice that it worked, even partly.

So here is the completed trick.

You need to :

manually bypass nLoader a 1st time to be able to install a non-CAS OS 4.5.1+
and manually bypass nLoader a 2nd time, for the 1st newly installed OS reboot
This will make OS 4.5.1+ boot properly and it'll then update your Boot2 partition, thus removing nLoader. You won't have to do this again.

You may just hold

while the OS is installing itself, to be sure you don't miss the reboot.
You may also press reset as soon as the calculator reboots after receiving the OS, and then hold

before releasing it.