Does the recovery state anything about a corrupt cache? Usually wiping data or cache is the way to go and fixes this issue easily. Since you can get into fastboot mode, if all else fails just flash the stock image.
Sent from my XT1032 using XDA Premium 4 mobile app
Current Phone: Nexus 5 16GB Black D821
ROM: Stock KitKat 4.4.2 with root and TWRP (unlocked bootloader)
Current Tablet: ASUS Nexus 7 (2013) 16GB Black
ROM: Stock KitKat 4.4.2 with root and TWRP (unlocked boot loader)
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