[manjaro /]# mhwd-kernel -i
:: Synchronizing package databases...
core is up to date
extra is up to date
community is up to date
multilib is up to date
error: no targets specified (use -h for help)
the correct/complete command for this kernel would be:
mhwd-kernel -i linux515
You need to specify which kernel you want to install.
mhwd-kernel -l
lists all available kernels
mhwd-kernel -i $kernel_name
(pick one from the list)
installs it
ah sorry .
still nothing
[manjaro /]# mhwd-kernel -i linux515
:: Synchronizing package databases...
core is up to date
extra is up to date
community is up to date
multilib is up to date
error: no targets specified (use -h for help)
use pacman then - instead of mhwd-kernel
pacman -S linux515
followed by:
mkinitcpio -P
and
update-grub
I have zero idea why mhwd-kernel would do nothing - would not reinstall the kernel. 
Possibly because the system “thinks” it is already installed.
simply install another one?
mhwd-kernel -i linuxXY
it doesnt seem to have helped ?
[manjaro /]# update-grub
Generating grub configuration file ...
Found theme: /usr/share/grub/themes/manjaro/theme.txt
Found linux image: /boot/vmlinuz-5.15-x86_64
Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.15-x86_64.img
Found initrd fallback image: /boot/initramfs-5.15-x86_64-fallback.img
Warning: os-prober will be executed to detect other bootable partitions.
Its output will be used to detect bootable binaries on them and create new boot entries.
grub-probe: error: cannot find a GRUB drive for /dev/sdb1. Check your device.map.
grub-probe: error: cannot find a GRUB drive for /dev/sdb1. Check your device.map.
Adding boot menu entry for UEFI Firmware Settings ...
Root filesystem isn't btrfs
If you think an error has occurred, please file a bug report at "https://github.com/Antynea/grub-btrfs"
Found memtest86+ image: /boot/memtest86+/memtest.bin
done
to me it does
See the difference to the previous output?
See the:
Found linux image: ...
and
Found initrd image: ...
?
ah yes, should I try and boot ?
of course
you can always boot the live system again and chroot and keep working - if you need to
wish me luck
It’s got nothing to do with luck. 
ok, I’m booted into the installed linux !
But it skipped over the grub menu , I can’t select to boot into windows
Different problem - but likely caused by you having updated grub while in chroot.
simply run
update-grub
once again from the now working system
sudo update-grub
that is …
Do I use chroot or just under user ?
no
you are now in your working system - no need for chroot (manjaro-chroot is not available anyway from your normal system - it is just on the usb)
ok seems to have added windows !
Try it - confirm / make sure.
I just did , was able to boot into windows fine.
Thank you very much for your patience and help
No worries - anytime I can.