perfect participle or simple participle?

[keannu]

Is the following participle perfect or simple? I mean whether blamed is the past perfect tense or past tense. Why can't we think as he was blamed for something... ?

1. Blamed for something he hadn't done, he went to his room and cried.
= As he had been blamed for something he hadn't done, he went to his room and cried.

I guess it's because being blamed happened prior to his action of going to his room, but sometimes like in the following, we tend to interpret it as simple participle even though it happened before "went to", and I don't know the difference between 1 and 2.

2. Getting off the bus, he went to a supermarket.
= After he got off the bus, he went to a supermarket.

[5jj]

1. Blamed for something he hadn't done, he went to his room and cried. past participle
= As he had been blamed for something he hadn't done, he went to his room and cried. past perfect (passive)


2. Getting off the bus, he went to a supermarket. present participle
= After he got off the bus, he went to a supermarket. past simple

[keannu]

I'm sorry, but I asked for how to tell the two.