求救 求救

有大大可以教我 如何將ipad 4.3.1 降版到4.2.1 +jb 嗎
我爬文爬很久了
ipad 的畫面卡在

Got stuck on the AppleS5L8920XIOPSDO PIopManager::init() Failed to get AppleS5L8920XARM7M after 10 sec.
Got stuck on the AppleS5L8920XIOPSDO PIopManager::init() Failed to get AppleS5L8920XARM7M after 150 sec.
Got stuck on the AppleS5L8920XIOPSDO PIopManager::init() Failed to get AppleS5L8920XARM7M after 250 sec.