Dear espresso-machine-experts,
I have spent several hours this and last weekend going through post in several forums, youtube videos and how-to-guides looking for solutions to the problem I have with my espresso machine, but I think I need the expert help from some of you to diagnose the exact nature of my problem in order to find the right cure:

Background:
My sister gave me her app. five years old Oscar Nuova Simonelli, since she rarely used it and it didn't work to well. When trying to brew my first espresso, it turned out that the machine was in a really bad shape: the coffee was only lukewarm even though the boiler went on for a long time before the signal-light said 'go'.
She told me to descale it - a thing i suspect she haven't done for a couple years. She directed me to this video: https://www.youtube.com/watch?v=-eXlC-Eo1h0 - which I followed.

Problem:
After running the procedure, the machine stopped heating at all. The heating lamp is not lighting up at all.

Diagnosis?:
My sense from going through the many discussions of descaling and related issues online, I suspect that the descaling I pursued have released a big amount of lime scale that is by now blocking the passage of water (and thereby also the citric-acid I need to send through to descale it).
(Or is the thermostat, boiler or other functions that is malfunctioning now?)

What should be my best next steps to carefully diagnose the exact problem?

Possible procedure for fixing:
Do I need to disassemble the machine and wash all the inner parts piece by piece?

Bonus info:
Tap water in Copenhagen has very high level of lime, and I think the machine have been used with tap-water on and off over the years. By looking inside, it appears that the boiler might be pretty filled with scale - see attached image

I hope you might be able to give me some useful advice as to how I should proceed.

Sincerely,
Rune, a newbie to espresso-machines

I just opened to have a look inside the boiler - with lots of nasty stuff:

That thing is bad!!....I would definitely remove the boiler and other vital parts and soak in an acid bath...You need to do some serious cleaning to get it back up to speed.

I'm in agreement, there is nothing you can do without just removing the components and soaking them. I love my Oscar, I paid $500 for mine.. but free that's a steel! Fix it! I don't think you'll be disappointed.

Thanks. Any recommendation for guides for this procedure?

https://www.youtube.com/watch?v=yK_z80DrqdI

This is the video that helped me...I also added the gicleurs when i tore mine down...My boiler was like brand new when i finished up!

http://s156.photobucket.com/user/GandBt ... 4231/story

Thanks, this one i already found. Would like to have written guide to make sure i dont do anything wrong. Is there any around?

This is really bad.... :

Everything looks nice and shiny now. And The video is a nice guide.
I'm wondering if the small valve in this tube is misplaced and need replacement?