
Well to overcome this misterhidayat.blogspot.com will share tutorials and ways to bring up the phoenix os boot menu with the easy bcd software. Check out the steps below
How to Fix Phoenix OS Boot Not Detected
1. First, please download the installer exe file and the phoenix os iso file with the same version. Next install the exe file as usual.
Read Here: How To Install Phoenix OS Dual Boot Windows
Do not restart the device.
2. Create a folder with the name “android-5.1.1” (without quotes).
3. Mount the ISO file with software Ultra ISOor Power ISO. Then copy all files to “android-5.1.1” folder.
5. Copy the missing files from the Phoenix OS folder you installed (data.img and system.img) to the “android-5.1.1” folder.
6. Next, please download and install Easybcdand software Bootice,
7. Open Easybcd, select add new entry, select new option, and select install, after that, click configure.
8. Copy the code below and enter it into the opened file;
default=0
timeout=0
splashimage=/grub/android-x86.xpm.gz
root (hd0,1)
title Android 5.1.1
kernel /android-5.1.1/kernel quiet root=/dev/ram0 androidboot.hardware=android_x86 video=-16 SRC=/android-5.1.1
initrd /android-5.1.1/initrd.img
title Android 5.1.1 (video=LVDS-1:d)
kernel /android-5.1.1/kernel quiet video=LVDS-1:d root=/dev/ram0 androidboot.hardware=android_x86 video=-16 SRC=/android-5.1.1
initrd /android-5.1.1/initrd.img

Don’t save it yet, now you see the line “root (hd0,1)”,
9. Open Bootice, find where your Phoenix OS is installed in the section Destination Disk, you can see the number of partitions and where the phoenix os is installed. change order “root(hd0,1)” to phoenix os after that, save.

9. Restart the PC and please check whether the phoenix boot appears or not.
That’s the above how to overcome the phoenix os failed to boot because the phoenix os boot menu was not detected. Good luck!