求助：iPad3 4G 升级6.1 提示未知错误 -1, 怀疑是基带问题，不知道有人遇到过没

贴上关键位置的日志:

update_baseband: querying baseband info
bbupdater: BEGIN: Querying info at stage initial
bbupdater: BEGIN: Preparing Initial stage
bbupdater: Requested boot mode: kBBUBootModeNone
[nand_part_core:INF@3169] next 98 pages of boot blocks written with LLB image of size 150080 bytes
[nand_part_core:INF@3172] final 156 pages of boot blocks written with random data in full page format
bbupdater: Creating transport, attempts remaining 1...bbupdater: FAILED(kBBUReturnIOError)
bbupdater: Creating transport, attempts remaining 0...bbupdater: FAILED(kBBUReturnIOError)
bbupdater: Modem not responding
bbupdater: Forcing into first stage
bbupdater: Creating transport, attempts remaining 1...bbupdater: FAILED(kBBUReturnIOError)
bbupdater: Creating transport, attempts remaining 0...bbupdater: FAILED(kBBUReturnIOError)
bbupdater: END(kBBUReturnIOError): Preparing Initial stage
bbupdater: END(kBBUReturnIOError): Querying info at stage initial
send_bbupdate_status: sending baseband update status to host
update_baseband: bbupdater error:
0: RamrodErrorDomain/3ec: update_baseband: failed querying baseband info
1: BBUpdater/0
unable to convert ramrod error 1004
restore failed with CFError:
0: AMRestoreErrorDomain/ffffffff: failed to update device firmware
1: AMRestoreErrorDomain/ffffffff: ramrod firmware update failed
2: RamrodErrorDomain/3ec: update_baseband: failed querying baseband info
3: BBUpdater/0
attempting to dump restore log
writing log file: /mnt1/restore.log