Bread maker. For dummies. Help please

[DontBuyANewMumCashmere]

I have a Kenwood BM450 (if this is relevant.)

I made a loaf yesterday with 100% wholemeal flour, made from a local water Mill / stone ground place.
Not sure if I should have made it with 75% wm flour and 25% plain?

Furthermore it came out heavy as a brick, very dense, I could have killed someone if I'd thrown it at them. Seriously!

Troubleshooting says either too much flour, not enough yeast or not enough sugar. I definitely used the exact amounts, but does anyone have a good tip for too dense a loaf?

I still tried it and it tastes of bread, so not a total failure.
TIA

Said dense loaf.

It certainly does look dense.
Things to consider:
Age of flour? (protein levels drop with age)
Age of yeast? (dead or alive)
Quantity of water? (a wet dough gives a more open structure)
When you added the salt, was it too near the yeast? (salt kills yeast)
When loaf was rising, did you go on time or size?
Also, I would generally add a little oil makes the structure softer) and also substitute, as you suggested, 25% of the WM flour for White.

Just seen that you used a bread maker.........doh! Sorry, I was thinking made by hand. Questions regarding flour, yeast and salt still apply though. Also, it may seem a very silly question, but I take it that you were using strong bread flour weren't you?

Has the machine broken it hasn't risen at all.