If the pressure is 0 and no hot water in the property.
We need to check the pipes below the boilier
This is location at the bottom of the cupboard where the kitchen papers are located.
They need to pull up this black lever up of 3 seconds and immediately pull it down to close.
Then check the bar moving up to 1 and do not exceed 2
NOTE: Be very careful not to over pressure the boiler since it might break