How to determine if my Raspberry Pi still usable

Getting very hot is normally a sign of a damaged component which maybe internally shorted out and drawing too much current. Can you identify which component is getting hot?

all the main processor chips and the bigger chips seems hot.... i will try to identify more. i didn't place too much hope on it ...

The lowest maximum die temperature rating (commercial) for a lot of modern ICs is 70 deg. C (158 deg. F) which is a lot more than "seems warm" to human touch. So just

about any IC, especially ones with large transistor counts such as SoCs and RAM will "seem warm" and can still easily operate even when they feel hot to very hot. The ICs

are specified to run at this temperature for the rated life of the IC which is usually in the 10's of thousands of hours. Running cooler than that can extend their life,

Your problem started when you changed the OS on the flash card. Assuming you did nothing else that may have damaged the Pi my guess would be that is where your

problem is.

Just FYI,

There are three standard maximum die temperature ratings. The maximum industrial die temperature rating is 85 deg. C (185 deg, F). I believe the Pi SoC is rated as

industrial. The maximum military die temperature rating is 125 deg. C (257 deg. F), hotter that boiling water! There are also ICs that have their temperature ratings

specified by the manufacturer because they do not fit into the standard rating system.

When I first started in electronics in 1976 I worked on four Sentry IC testers from Fairchild. The high speed timing section used a very fast and power hungry type of logic

circuit called ECL (Emitter Coupled Logic, sometimes called Current Mode Logic). If the IC didn't literally burn your finger when you touched it it was probably bad!

The lowest maximum die temperature rating (commercial) for a lot of modern ICs is 70 deg. C (158 deg. F) which is a lot more than "seems warm" to human touch. So just

about any IC, especially ones with large transistor counts such as SoCs and RAM will "seem warm" and can still easily operate even when they feel hot to very hot. The ICs

are specified to run at this temperature for the rated life of the IC which is usually in the 10's of thousands of hours. Running cooler than that can extend their life,

Your problem started when you changed the OS on the flash card. Assuming you did nothing else that may have damaged the Pi my guess would be that is where your

problem is.

Just FYI,

There are three standard maximum die temperature ratings. The maximum industrial die temperature rating is 85 deg. C (185 deg, F). I believe the Pi SoC is rated as

industrial. The maximum military die temperature rating is 125 deg. C (257 deg. F), hotter that boiling water! There are also ICs that have their temperature ratings

specified by the manufacturer because they do not fit into the standard rating system.

When I first started in electronics in 1976 I worked on four Sentry IC testers from Fairchild. The high speed timing section used a very fast and power hungry type of logic

circuit called ECL (Emitter Coupled Logic, sometimes called Current Mode Logic). If the IC didn't literally burn your finger when you touched it it was probably bad!