Phone won't boot and won't enter recovery, even after reflashing TWRP

I have a Xiaomi Redmi 2 phone on which I installed Cyanogenmod. So, after upgrading manually, the phone won't boot anymore (neither into recovery nor into the system). Only fastboot works. (Probably because whatever was in the recovery partition was lost).

So, I can get into fastboot mode, and the phone reacts correctly:

# fastboot devices 

78768331
 fastboot



# fastboot getvar version

version: 0.5

finished. total time: 0.003s



# fastboot oem unlock

...

OKAY [  0.003s]

finished. total time: 0.003s



# fastboot erase recovery

erasing 'recovery'...

OKAY [  0.041s]

finished. total time: 0.041s

Then I tried flashing a new TWRP recovery, that I just downloaded:

# fastboot flash recovery twrp-3.0.2-0-aries.img

target reported max download size of 268435456 bytes

sending 'recovery' (11136 KB)...

OKAY [  0.353s]

writing 'recovery'...

OKAY [  0.290s]

finished. total time: 0.642s

TWRP was the recovery I had installed before.

I also tried flashing the stock recovery, but it still won't boot.
What else can I try?

edit: I can boot a recovery image using fastboot boot recovery.img.