leaving the hibernate state

[Pierre Frenkiel <pierre.frenkiel@gmail.com>]

hi,
I installed pm-hibernate on my laptop, and it seemed to work,
i.e. I got a black screen 10 to 15 seconds after issuing the 
pm-hibernate command, but I was unable to wake-up the laptop.
Looking on Internet I found tons of documentation about suspend and
hibernate, but amazingly, not a single line about the way to leave these 
states. 
Of course, I tried almost all the keyboard keys, without success, and 
all I could do was to  hold down the power button, which gave the normal
startup, with a "recovering journal".
My laptop is a Lenovo ideapad 110, running Stretch
Should I configure something to use pm-hibernate?
I have in syslog lines like:

    Hibernation image not present or could not be loaded.

but I didn't find how to  fix that.(adding resume=/dev/disk/by-uuid/...
in /etc/default/grub changed nothing)

best regards,
--
Pierre Frenkiel