Hi!
Find parent means the node is trying to find its way to the gateway - and if this repeats it cant.
Its either a range issue or a power issue. You can start by checking the gateway serial log and see if there is any info.
Also, have you added a capacitor on the radios? This is very important since the radio is sensitive to power spikes.
It this doesnt work start with changing the power source and check your wirings / ground connection on the node.
Also you can try to move the node closer to the gateway - if this works and you have some distance between node and gateway you should consider a repeater.