In the lack of the clarifications requested, I can confirm that I do not think that the issue with the electric meter can be blamed on the landlord, while the fact that you were not told where the water tap control is could, assuming that the location of the tap in the flat is not easy to find or is not accessible.
If that is the case, the unavailability of water making the flat uninhabitable, you might have a claim against the landlord for the reasonable cost of an accommodation in the weekend, but you must be prepared to a fight because they will certainly say that you were told where the tap was and/or that the tap was easy to locate.
If someone forged your signature on the inventory, that could be a criminal offence, and, if that's the case, I think you should consult a solicitor for legal advice.
Of course, if you have not signed the check-in inventory for acceptance, you will not have accepted it, but you should be aware that refusing to sign for acceptance, and also failure to provide comments on the inventory even if you don't want to sign it, could be considered a breach of the tenant's obligations (this, of course, in case the inventory was not fraudulently signed by someone else).
I hope this information is helpful and I wish you the best.
Please do not hesitate to contact JA again if you need help and you may ask to speak with me directly if you wish ("For TheLawLDN only").
I would appreciate it if you could provide a positive rating, if you wish so of course.
Thank you very much.