Dell Venue 8 LTE 3840 OTA Package

Hi,

I was trying to install  custom recovery and unfortunately my tablet not stuck on Sleeping android bot with red exclamation. I can only start recovery but cannot boot in fastboot. Can any one help with OTA package to restore my tablet using ADB sideload. I tried lot of options through internet Stock images etc. but every time i get an error "Signature verification failed" or "package.zip does not exist".  Can anyone help me or link to 4.4.4 OTA package?

Thanks

Riz Sid