Help needed to boot into Recovery

[Maged Samuel]

Hi,
I'm on an LG G2 D802 (International). I've successfully installed CM12.1 without any problems using TWRP. I just forgot to flash the gapps while I was in the recovery mode so I want to get back to TWRP again but unfortunately I'm not able to get to it using the shortcuts (volume down + power...etc) because all it shows me is a menu asking me if i want to factory reset my phone with a yes/no answer. I tried downloading 2 different apk files from the internet but none of them works! (one of 'em crashed and the other is pretending that it will go a head and boot into recovery but nothing really happens!). What's wrong and How can I get back to TWRP using an apk that actually works!?

Edit: I figured out how to boot into recovery but i get an error flashing the gapps saying in red: Error executing updater binary in zip blah blah open_gapps-x86-5.1-nano-20160311.zip
what might be the problem? the cm12.1 is useless without google apps so I appreciate your hints on what might be wrong. Thanks in advance

 

[B. Diddy]

Moved to the G2 Rooting forum.