D-Link ipcam DCS-932L

Hi everyone,
I have a D-Link DCS-932 ipcam and reading the following page https://openwrt.org/toh/d-link/dcs-930l I installed a ram version of openwrt. Now I'd like to upgrade (sysupgrade) the installed version but I cannot perform any update on the camera. I tried from both Luci interface and recovery web page ( but nothing happend.
Digging into the camera through ssh I discovered that it doesn't have mtd installed and any upgrade fails with the following error: No mtd found.
I tried to manually install mtd from ramips folder but I get an architecture error. I cant flash any more my cam. Can You help me to install a factory or the original firmware?

Thank for your helps.