Help & Hinder, a new take on combat actions

In session 3, Serrin our rogue was faced with having to pick the lock of the big metal door in a hurry, what with being chased by tons of goblins and all that. I house ruled on the fly that he could either rush it in on turn but at disadvantage, or take 5 turns and do it normally.

When he decided to go ahead and rush it, Grom decided to "Help" him, therefore removing the disadvantage. I wanted to try the basic rules so I let things happen but already, it didn't make much sense how an half orc druid with no lock experience could just "help" to such extend.

Afterwards, I thought about this and came up with these two little house rules for Help and Hinder.

HELP:

• You can lend your aid to another creature in the completion of a task. The creature you aid gains advantage for the next relevant ability check he makes to perform that task before your next turn. To determine if you succeeded in providing any relevant help, do an ability check as the target would but with a lower DC (Hard to Normal, Normal to Easy, etc).
• Alternatively, you can aid another creature in one (and only one) of it's attack against a creature within 5' of you. If the creature you help attacks the target before your next turn, the attack roll is made with advantage. To determine if you succeeded, make a DEX(Feint) or INT(Feint) contest check against the target creature DEX or INT.

HINDER:

• You can distract or otherwise hinder another creature within 5' of you. The creature has disadvantage on the next relevant ability check or attack roll it makes before your next turn. To determine if you succeeded, make a DEX(Feint) or INT(Feint) contest check against the target creature DEX or INT.

Edit: Been using these house rules for some time now, works like a charm and really makes more sense. Plus, having to roll for it makes the action more involved for the PC actually trying to help.