Ok, I have a strange one that I have never seen before.
So let me describe what I did. I took the air box, plenum, throttle body off. Disconnected various plugs to get the coils off and removed the valve covers to replace the gaskets. Job was completed, so I connected and hooked everything back up.
The friend of mine whom's odyssey I am working on also had an oil leak from the oil pump. The van has 145K miles on it so I got the timing belt, water pump, oil pump new serpentine belt the whole nine yards, new tensioner pulleys hydraulic auto tensioner the works. I was going to do all of this on the van. I could not get the crank bolt off. Broke 2 impact sockets, an extension and bent a breaker bar. Tried to use a torch to heat the washer still nothing. Did not budge. So I called a shop and said I couldn't break the bolt and they told me to bring the van to them and they would break the bolt and re set it so I could get it off at home. I put everything back together and started the van. It ran like crap with lugging and sputtering, so I shut it off. Went over everything again and realized I had forgot to hook the hose up on top of the plenum. (Breather hose). So I hooked it back up and went to start it again. This time when I turned the key the motor turned but would not start. Here is where it gets weird and I have never seen it before.

I turn the key and the motor spins but does not sound like a starting engine. It just spins. Almost acting like there is absolutely no compression. The motor just turns. I checked for spark at the coils and there is spark. I checked for fuel. Fuel flows fine. I checked all the relays both the relays and the terminals they plug into. Everything is fine. The reason its so weird. is the motor turns but does not sound or look like a "cranking" engine. It just turns the only noise you hear is the starter turning the engine. Its almost as if the pistons are not moving but I know they are. I did check to make sure the timing belt was still attached and it is. I checked the wires from the camshaft and crankshaft sensors and they are all fine. I am at a complete loss. I have never seen an engine just turn. I have heard them crank with no start and making the sound its trying to do something but this one just turns as if there is no resistance. It started for a split moment but now just turns. I have went over everything I can think of including smacking the starter with a hammer and piece of wood to see if that would get it to kick over. I'm at a total loss......

 

This is what it is doing...Everything is turning and moving.

 

Are you reading any codes? CEL?
First of all, re-check all connections and read the codes.
And here's the most important piece: you can break the bolt easily with the following two tools: the Honda 50mm crank pulley holder and a 3 foot 3/4" drive breaker bar. Do not use 1/2" drive breaker bars since they can be bent or broken. Place a 2 foot 3/4" drive extension on a jack stand and you should be able to break the bolt free with ease. The Honda tool should be held by the LCA the shortest way possible.

 

I have done alkl of that and have the 50MM socket. I went through the connections and checked all the relays last night again and nothing. It has to be something electrical as it started once just ran like crap because that breather hose was not hooked up. I hooked it up and tried to start it again and now this

 

No codes?

 

No no codes. All relays work, all relay sockets have power, everything works the spark plugs are covered in fuel, the spark plugs produce sparks. The throttle body works just fine. Its like the engine turns but doesnt crank. Look at the video above.

 

Does the immobilizer light (green) come up as expected (two flashes or so IIRC)?
Can you try with another key?

 

Yes and yes same thing.

 

I would suspect a fried ECU at this point.

 

Ok so the guy who owns this van, we took it to a shop that can get the crank bolt off. Well the mechanic at the shop said that 12 valves were bent and that is why it has no compression. that when I tried to take off the crank bolt it jumped the timing. I didn't think it being off a tooth or two would bend 12 valves without making any noise other than a crappy running engine due to the breather tube being off. I never heard any metal to metal contact or anything like that. But apparently I destroyed 12 valves from what he said.....