I did something similar to yours lately and here is what I did:

@api.one
def resolve_payment(self):
    company_id = self.company_id
    journal_id = self.env['account.journal'].search([('type', 'in', ['bank', 'cash'])], limit=1)
    payment_method_ids = self.journal_id.inbound_payment_method_ids or self.journal_id.outbound_payment_method_ids
    payment_id = self.env['account.payment'].with_context(active_ids=[self.id], active_model='account.invoice').create({
        'amount': self.residual,
        'journal_id': journal_id.id,
        'payment_method_id': payment_method_ids and payment_method_ids[0].id
    })
    payment_id.action_validate_invoice_payment()
    return payment_id.id

I added this code in account.invoice model

I called this method after calling action_invoice_open method

please help... i'm stuck in here tooo