This instruction has helped somebody else, so you too can try.

I think the problem is the kernel.

I would go back to Android (6.0) and start everything from scratch again. (Root, multirom, then install secondary roms.)

This is how I set up and use my Nexus 5:
(I mentioned Ubuntu Touch here because I started with that first, then I moved to Sailfish OS.)

1. unlock boot loader
- adb reboot bootloader
- fastboot oem unlock
2. root (Info)
CF-Auto-Root
3. MultiRom with Ubuntu Touch repo (Info and Info about multirom):
- install 1-MultiROMMgr_withUT.apk (multirom with UbuntuTouch repo) with adb (Info):
- adb install 1-MultiROMMgr_withUT.apk
4. reboot recovery and install:
- kernel: kernel_kexec_hammerhead_601.zip
- multirom recovery: multirom-20160207-v33-hammerhead.zip
5. reboot android, start MultiRom and install Ubuntu Touch
6. SailFish OS (Info):
- boot into recovery: Advanced -> MultiROM -> Add ROM
- Choose "SailfishOS" as ROM type.
- Choose first CyanogenMod ZIP and then SailfishOS ZIP. Click install.

I have uploaded all files to my storage and made them available for you. So you don't need to hunt them together from the websites I linked in as Info at each step. However, I recommend to read them to get an overview.

I usually use one of these twrps. (With the newer one you can install Ubuntu Touch but cannot flash a zip on a secondary from. With the older you can flash a zip on a secondary from, but cannot install UT.): TWRP_multirom_hammerhead_20150630 or TWRP_multirom_hammerhead_20160210