最后一步刷自制固件卡在sending iBEC 进度73.9%，求助如何解决。
NOTE: using cached version data
Found device in DFU mode
Identified device as n90ap, iPhone3,1
Extracting BuildManifest from IPSW
Product Version: 5.1.1
Product Build: 9B206 Major: 9
Device supports Image4: false
Variant: Customer Erase Install (IPSW)
This restore will erase your device data.
Found ECID 4016148608396
Getting ApNonce in dfu mode...
checking for local shsh
Using cached SHSH
Using cached filesystem from 'iPhone3,1_5.1.1_9B206_Custom/038-4292-008.dmg'
Extracting iBSS.n90ap.RELEASE.dfu...
Personalizing IMG3 component iBSS...
reconstructed size: 67909
Sending iBSS (67909 bytes)...
[==================================================] 100.0%
Nonce:
checking for local shsh
Using cached SHSH
Extracting iBEC.n90ap.RELEASE.dfu...
Personalizing IMG3 component iBEC...
reconstructed size: 244037
Sending iBEC (244037 bytes)...
[===================================== ] 73.9%

虚拟机的话 你在开机前在设置里把usb3.0换成2.0