boiler not working after repair to a pipe.

[shaner500]

hi all i had to repair a pip for a friend on his central heating. a22mm pipe i just cut and put a compression joint on it.
i had turned off water at stopcock and turned power off to boiler
there was a drain of valve on the flow pipe i opened that with a hose connected to it. then did the pipe repair. restored everything back.
and now the boiler is not working.
its a baxi solo15 he.
i get red light on green boiler light flashing and power light flashing.
on the fault panel it says low flow. but in the installation manual this code says dry fire.

any help appreciated
cheers