Fastboot permission denied error in Asus Zenfone 2

I went into regular recovery mode to wipe cache and do factory reset to flash clean Asus ROM from XDA. I first went to wipe cache and it felt like it was taking way too long, so I turned off the phone and tried to turn it back on, and now all I get is a dead Android. I found this thread on XDA to unbrick the phone but when I try the steps I am getting permission denied message while using fastboot. I cannot flash TWRP via fastboot either. C:\Users\bdelc\Downloads\android\Fastboot>fastboot flash recovery recovery.img target reported max download size of 536870912 bytes sending 'recovery' (11864 KB)... OKAY [ 0.628s] writing 'recovery'... FAILED (remote: Permission denied) finished. total time: 0.809s C:\Users\bdelc\Downloads\android\Fastboot>fastboot flash boot boot.img target reported max download size of 536870912 bytes sending 'boot' (11850 KB)... OKAY [ 0.619s] writing 'boot'... FAILED (remote: Permission denied) finished. total time: 0.804s C:\Users\bdelc\Downloads\android\Fastboot>fastboot flash fastboot droidboot.img target reported max download size of 536870912 bytes sending 'fastboot' (14800 KB)... OKAY [ 0.712s] writing 'fastboot'... FAILED (remote: Permission denied) finished. total time: 0.888s C:\Users\bdelc\Downloads\android\Fastboot>fastboot flash recovery twrp-2.8.7.1-fhd.img target reported max download size of 536870912 bytes sending 'recovery' (14456 KB)... OKAY [ 0.844s] writing 'recovery'... FAILED (remote: Permission denied) finished. total time: 1.012s