Error on recovery mode

Hi,

I got battery and display changed for my Asus Zenfon 2, after a few days it's not booting up. It is stuck on ASUS logo. I tried to flash it by entering into recovery mode but it's keep on displaying error with android logo. Don't know exactly but it seems like it is not detecting internal flash memory for boot process.

Please let me know how to resolve this.

Thanks

AJAY