Every time Marco tried to force the baseband (the 3G modem firmware) into submission, iTunes screamed 935. It was Apple’s digital guard dog, a hardware-level handshake failure. The 3G iPad 2 had a unique security chip—the Baseband Bootloader —that refused to talk to any server except Apple’s official activation servers. And those servers no longer recognized the ancient iOS 9.3.5 signatures.
Even with a successful untethered bypass, there are "legacy" issues to keep in mind: ipad 2 935 icloud bypass untethered
: iOS 8.4.1 and 6.1.3 have fully untethered jailbreaks . Once downgraded, the device stays unlocked and jailbroken even after a power cycle. ⚠️ Important Limitations Every time Marco tried to force the baseband