Skoda octavia 2008 tdi

So i bought a new battery, little lower ah than previous one, it was flat when i got it, i had to jump start it, after that it ran and drove without anyproblems, i was away for a week and came back to use the car, it did not start again, the glowplug light wont come on and i dont hear the fuel pump, so i recharged the battery and still same problem, im thinking maybe its bad battery i got from the store, basically it seems immo doesnt let the car start, i think its bad battery i got because when the car was runming it showed me on the mfd when car door was open even when the key wasnt in. I took the car to mechanic who said that computer shows theres problem with speedometer he sent it to be checked but it seemed fine. So now im completely lost for what might be the problem.