HDB flat can go up only if lucky, so usually cannot one.
If you seriously want to find one, go to those just build one with
low to no occupancies. Usually, those will not be locked, so you
can go in easily. This is especially true if the lift not even
working yet. But also means have to exercise a bit. A few of those
I go up are these type of cases. (Err... hope no one learn idea
where to go sucide from me 
).
