What tests are typically done?

I'll try to make this short and informative.
Son, current age 15, 8th grade
Since 1st grade, requested testing for LD or other problem every year. 3rd grade finally got 504.
Continual battle to scrape by on grades, asked to have him held back. Was told no, then finally they failed him in 6th grade.
They said they tested him in 1st grade, 3rd grade after 4th grade and again his second year in 6th grade.
Each time I'm told he has no LD, he can do the work, he just doesn't so he did not qualify for ESE or any assistance. They continually say he's lazy and unmotivated. Finally second 6th grade he was given and I.E.P. - other medically qualified after he was diag with ODD, BiPolar, ADHD and EOD. His IEP classification has gotten him nothing except an ESE strategies class. He gets an A in this class, but gets F's in all his other classes (don't understand or agree with the A, but that's a different story.)
He can not write legibly, can not spell and is completely confused by simple math and can not understand the simplest of word problems.

NOW, 10 years later his case manager is telling me that he was never IQ tested. I'm very confused, I thought this was needed to test a child for LD. I can't find anywhere that tells me what tests they do, and how they each look for LDs. How do I know if he's actually been tested properly. How many different tests are there and which ones are more apt to find a hidden problem? Can anyone tell me these things, or point me in the direction to look?

Now, he's so far behind in school, and he's lost so much of his childhood because of this continual insistence of the school that he just refuses to do his work. He's been held out of P.E. music, art and recess to continue his class work. What repercussions are there, if this child has continually been bombarded with the continual failures and consequences of living with some form of LD and the school never testing him properly?